I'm new to D&D 5e and monster weapons and attacks are confusing. I want to clear this up before I allow this, because it could be a huge mistake.
If my PCs kill a monster and decide to take the monster's weapon, do they get everything that goes along with it from the monster action section? So as an example, I have just killed a Redcap and I take his sickle — does that mean I get the "wicked sickle" action which is a +6 to hit, reach 5ft for 2d4+6 slashing damage, or is it just a sickle?
Really it is the modifiers that worry me. Some of these weapons have some crazy to hit bonuses and I kinda need to know if that is okay to let them have that or not.
Best Answer
That to hit bonus was not from the weapon
Monsters get their bonuses from their stats and features, not from their weapons. For the DM's convenience, these bonuses are incorporated in their stats block.
Let's take the Redcap attack for example:
The Wicked Sickle is not just a mere sickle - it is bigger and looks more like a weapon than an agricultural tool - but it doesn't give the +6 attack modifier.
The "+6 to hit" is from the Redcap's Strength modifier +4 and its proficiency +2. "2d4 + 4" damage is from 2d4 (the Wicked Sickle itself) and +4 (STR modifier).
If a PC wields the sickle, they doesn't get the proficiency bonus (the Wicked Sickle is neither Simple nor Martial weapon), and should add their own STR modifier instead of the Redcap's one.
Another example - a Bugbear's attack:
The Morningstar doesn't deal 2d8 + 2 damage. It deals 1d8 damage by itself, like a normal morningstar. The +2 is from the Bugbear's STR bonus, and x2 is from its Brute feature: