(5E) Melee weapons and melee weapon attacks AKA why can't i throw my warhammer when raging

D&D 5E uses the terms "melee weapon", "melee weapon attack", "ranged weapon", and "ranged weapon attack" reasonably consistently but fails, in my opinion, to explain them all that well. So, here's my attempt.

Weapons
A melee weapon is something found on the simple melee weapons table or the martial melee weapons table. You hold it and hit your foe with it. You can also throw it at them, though it might not be very effective when thrown.

A ranged weapon is something found on the simple ranged weapons table or the martial ranged weapons table. You either throw it at a foe (if it has the thrown property) or use it to launch some sort of missile at the foe (if it has the ammunition property). You can hold it and hit a foe with it but it will not be very effective.

Attacks
From the Combat chapter of the rules:

Hitting a target within your reach with an item that you are holding is a melee weapon attack. The ability modifier used is Strength.

Throwing an item at a foe or launching some sort of missile at them is a ranged weapon attack. The ability modifier used is Dexterity.

Thrown property
If a melee weapon has the thrown property then throwing it at a foe is making a ranged weapon attack but using Strength, not Dexterity. The weapon is still a melee weapon (not a ranged weapon), which is important for some features.

If a melee weapon doesn't have the thrown property, you can still throw it but you won't be as effective. It is considered an improvised weapon and will do 1d4 + DEX Mod damage. Your ranged weapon attack is with an item that is not on any of the weapon tables (improvised weapons are not actual weapons), so it uses Dexterity.

If a ranged weapon has the thrown property then throwing it at a foe is making a ranged weapon attack using Dexterity.

Finesse property
If a weapon (melee or ranged) has the finesse property then you can choose to use Strength or Dexterity for melee weapon attacks and ranged weapon attacks made with it, though you must use the same modifier for both the attack roll and the damage roll.

Other
There are also a few things that aren't weapons but are still used to make a melee weapon attack (using Strength) or a ranged weapon attack (using Dexterity): unarmed attacks, claw/bite/etc attacks and improvised weapons.

Summary
• "Melee weapon" and "ranged weapon" is based on which table the weapon appear in. Melee weapons use Strength; ranged weapons use Dexterity.
• "Melee weapon attack" and "ranged weapon attack" are based on what you are doing.

What are you doing?	Melee Weapon	Melee Weapon (thrown)	Ranged Weapon (thrown)	Ranged Weapon (ammunition)
Hitting someone while holding it	Melee weapon attack Strength	Melee weapon attack Strength	Improvised melee weapon attack Strength	Improvised melee weapon attack Strength
Throwing it	Improvised ranged weapon attack Dexterity	Ranged weapon attack Strength	Ranged weapon attack Dexterity	Improvised ranged weapon attack Dexterity
Launching ammunition from it	N/A	N/A	N/A	Ranged weapon attack Dexterity

• If the weapon has the finesse tag then you can choose to use either Strength or Dexterity, regardless of the type of attack.

The game is pretty consistent about the difference between "attack with a melee weapon" and "melee weapon attack". For example, Barbarian Rage damage bonus requires a "melee weapon attack using Strength" and therefore doesn't apply to thrown melee weapons or thrown ranged weapons.

Concentration

A few weeks ago I gave my players a pop quiz about concentration. Researching the quiz taught me a lot about the rule, especially about how many things require it.

Q1. What specific things require concentration?

• Casting a spell that has duration "Concentration".
• Casting a spell with a casting time longer than a single Action or Reaction. This includes all ritual casting.
• Readying a spell.
• Using a feature. For example, Draconic Presence (Draconic Sorcerer lvl 18), Visions of the Past (Knowledge Cleric lvl 17), Invoke Duplicity (Trickery Cleric lvl 2), Dark Delerium (Archfey Warlock lvl 14), Minor Alchemy (Transmutation Wizard lvl 2). This might include the Paladin and Cleric Holy Water ritual and the Warlock pact Weapon ritual (the rules don't specify).
• Using a magic item. For example, marvellous pigments, ring of djinni summoning, ring of shooting stars.

Q2. What can break concentration? What is the roll and DC, if applicable?

• Doing something else that requires concentration (automatic).
• Entering Barbarian Rage (automatic).
• Taking damage (CON saving throw, DC is half the damage, minimum 10).
• Being incapacitated (automatic).
• Being killed (automatic).
• The environment around you (CON saving throw, DC varies).

D&D 5E Weapon Analysis

Putting the weapons into a PivotTable shows some interesting properties.

Weapon PivotTable (click to embiggen)

What do we learn?

Damage comes from size. Light is 1d4, one-handed is 1d6, versatile is 1d8/1d10, two-handed is 1d10. Martial weapons are a die size larger. Reach weapons are a die size smaller, as are throwing weapons.

There are no two-handed heavy weapons using simple proficiency, and only one two-handed non-heavy simple weapon. I guess the designers figure that weapons of that size require martial skill.

There are no finesse bludgeoning weapons. The words "finesse" and "blunt instrument" do not go together.

Tridents are bad.

Handaxes are good (especially when dual-wielded by monks).

There are no one-handed slashing weapons. This is strange, because this is what I would call a "scimitar". I think what the game calls a "scimitar" is more like a machete or parang. If you added a martial slashing weapon, which did 1d8 damage, called a "sabre" or "falchion", it probably wouldn't break the game. It might be another option for rogues if you made it finesse.

Quarterstaves are weird. As far as I've encountered them, a "quaterstaff" is a heavy wood staff, shod with iron at one or both ends. This is not a weapon that can be used one-handed with a shield, yet in D&D it can be used one-handed, with a shield, while taking advantage of Polearm Mastery!

Hiding in D&D 5E

Hiding is poorly explained and/or poorly understood. Here's my take on it.

Summary

If something is "unseen" then you can't see it but you probably know where it is. If it is "hidden" then you can't see, hear or smell it and you might not even know it is there at all.

Unseen

You can't see the thing. You may or may not know the thing is present, depending on its noise or smell or on signs of its passage.

It has not taken any steps to hide its presence. If it had, it would be Hiding (see below).

How does a thing become Unseen?

There are many game effects that can cause a thing to become Unseen but they generally fall into one of two effects - concealment and lack of light.

Concealment is when there is something between you and the thing. For example: mist, foliage, smoke, squid ink, magical darkness.

Lack of light is when there is nothing between you and the thing but there still isn't any light illuminating it. Usually this when the thing is in an area of mundane darkness. It is also caused by you having the blinded condition.

How do I know where an Unseen thing is?

You know roughly where it is (on a grid, you know its square/hex) because you can hear it or smell it or see its footprints or perceive its location in some other way.

Can I attack an Unseen thing? Can it attack me?

Yes and yes.

If you cannot see it and it can see you then you have Disadvantage on your attacks.

If it cannot see you and you can see it then you have Advantage on your attacks.

If neither of you can see the other then you both attack normally (the Advantage and Disadvantage cancel, though other sources of Advantage/Disadvantage might still apply).

But… You can't target it with any attack or spell or feature that includes "that you can see" in its targeting. Note that this includes attacks of opportunity.

Hidden

Someone has actively taken steps to conceal the thing's presence.

You don't know where the thing is. You probably don't even know the thing is there at all.

Creatures conceal their own presence by one or more of: Walking quietly and not causing signs of passage. Muffling clothing and gear. Breathing quietly. Masking scent (by walking downwind, for example). Erasing tracks.

Creatures conceal the presence of objects by camouflaging them.

How do I hide a creature?

By telling the GM, "My character attempts to hide" and explaining how theya re going about this. If you are in combat then this will require the Hide Action.

The appropriate Ability Check will probably be DEX\Stealth.

Note that being unseen is required for attempting to hide and remaining hidden. There are exceptions (the Wild Elf racial ability, for example).

Changing location is also usually required. If you duck behind a tree and attempt to hide without moving away then the attempt fails - everyone knows exactly where you are (there she is, behind that tree!).

How do I hide an object?

By telling the GM, "My character attempts to hide the object" and explaining how theya re going about this. Perhaps you are concealing it somewhere. Perhaps you are camouflaging it or disguising it as something else.

The Ability Check required will vary. It will probably be WIS\Survival; but might also be INT\Stealth.

Can I attack a Hidden thing?

Generally, no.

You can guess at a location and blindly attack if you wish, but your chances of landing the hit are low. On top of guessing the location, the thing is Unseen, so the penalties described above will apply.

Use an area-of-effect spell instead. :-)

Can it attack me?

Oh yes! Many classes (Rogue, for example) get great benefit from attacking from hiding.

Attacking from hiding usually breaks stealth. It may or not break unseen.

Can something be hidden but not unseen?

Yes, that's the definition of disguised.

How do I detect an Unseen or Hidden thing?

That depends on the situation. 

Sometimes you will automatically detect it. For example, an Unseen creature walking across snow making sound and leaving footprints.

Sometimes you can never detect it. For example, an invisible statue.

Most of the time it will be a contest between your WIS\Perception and its DEX\Stealth.

If you are trying to deduce its location then you might roll INT\Investigation.

Links

RPG.StackExchange.com: Search

ENWorld.org: A treatise on hiding

ENWorld.org: Why do so many DMs use the wrong rules for invisibility?