Disclaimer: These D&D Hack articles are meant as an exploration of Read As Written (RAW) rules and uses. There are going to be people out there (especially those DMs) who have a knee-jerk reaction and try to quash their players instead of work with them. To those people, just skip ahead to the fix please.
5th edition D&D is great. It has the intelligence of modern game design mixed with nostalgia and creativity we missed. Even years of playtesting did not necessarily catch every loophole and strange rules hack. So I would like to present to you a few things I have noticed… maybe they will help you.
Hack: A quarterstaff (PHB 149) can be used in conjunction with Polearm Master (PHB 168). Polearm Master allows a bonus action attack with the “opposite end” of the weapon. However, quarterstaff can be used one-handed. A wielder could Attack with a quarterstaff, then use a bonus action to attack with the opposite end, all while holding it one handed (and possibly equip a shield in the other).
Fix: This is an easy fix however. Just rule that the quarterstaff (and any other listed weapon) must be used two-handed in order to benefit from Polearm Master.
Polearm Master is one of my favorite feats to get that extra attack roll early on in the game. The reach weapons are extremely helpful as well (especially if you use some sort of grid for combat). In combination with the Sentinel feat, it will be extremely difficult for enemies to move around you.
But… what do I know…?