You've seen the ins and outs of close quarters many a time, and have learned how to punish missteps

If an enemy misses an attack (and it must be ruled a miss, not blocked by a shield or armor. In other words, you have a Miss AC equivalent to your AC minus your shield and armor bonuses. if they roll above your Miss AC but below your AC, it's ruled as a block), you may use your reaction to make a Dex check (DC of 20-DEX) to try and catch it. From there, you have a few options, each of which requires a check vs their saving throw:

-Break the weapon (if one is used): Requires STR check determined by DM

-Snap the limb (if it was an unarmed strike): STR vs CON

-Disarm the opponent (weapon only): DEX vs DEX

-Knock the opponent prone: STR vs STR

-Grapple the opponent: STR vs STR

-Pull in for a retaliatory strike: Make an unarmed strike roll with advantage