Is there a D&D 5e equivalent to the Monkey Grip feat from D&D 3.5e?

Question

While I was DMing a D&D 3.5 adventure, one of my players played a character with the Monkey Grip feat (because he liked the manga Berserk, where the hero has a giant sword). And it turned out that it was fun.

Now I DM for D&D 5e. I plan to play with this player again, and he might want to play a similar character.

Is there an equivalent to the Monkey Grip feat in D&D 5e?

For reference, in D&D 3.5e, the Monkey Grip feat (Complete Warrior, p. 103) allowed you to use an oversized weapon with a -2 penalty on the attack roll. For instance, a Medium character could wield a giant's greatsword as if it were a normal greatsword, or a normal greatsword as if it were a longsword.

Answer 1

You don't need the feat in 5E to wield oversized weapons

The DMG section on creating a monster provides rules for using oversized weapons under "Step 11. Damage" (p. 278; emphasis mine):

Big monsters typically wield oversized weapons that deal extra dice of damage on a hit. Double the weapon dice if the creature is Large, triple the weapon dice if it’s Huge, and quadruple the weapon dice if it’s Gargantuan. For example, a Huge giant wielding an appropriately sized greataxe deals 3d12 slashing damage (plus its Strength bonus), instead of the normal 1d12.

A creature has disadvantage on attack rolls with a weapon that is sized for a larger attacker. You can rule that a weapon sized for an attacker two or more sizes larger is too big for the creature to use at all.

Disadvantage is, on average, equivalent to -5 on the roll (dependent on what the total number required to hit is). You could justifiably create a homebrewed feat that improved this to a static -2 penalty instead of disadvantage, provided the DM approves (just in case you aren't the DM).

Answer 2

No.

In D&D 5e, there is no feat equivalent of the monkey grip feat. However, you can talk to you DM about being allowed to use a homebrew feat that is the equivalent of that feat.