Weapons with Technical Problems:
Beggar's Bazooka
-The Reload Rate is slightly slower than the firing rate of its stock counterpart, which leads to quickfire rockets.
-In a long-term fight, the beggar's will fire more rockets from just rapidly firing with M1 than a stock rocket launcher would after 4 rockets + 1 reload. This makes it powerful in high ground areas (say, defending badwater's first point from the cliff) because he can stay in the fight longer by spamming his primary attack button and get more rockets off
I would suggest fixing this would be the core of the beggar's reload rate. It shouldn't be able to load another rocket before it finishes the firing animation.
Weapons with Tactical Problems:
Short Circuit
-This weapon cancels out a lot of spam in a short amount of time, and by switching weapons and gaining metal from your dispenser, or picking up a nearby ammo pack, it can last in the long run when dealing with heavy explosives fire with very little support from teammates.
-The firing rate is the problem, as well as the low-ammo cost to use.
It's frustrating to play against as an explosives class because sentries can be tough to deal with when coupled with any team support. A bullet-intensive class can handle a sentry with an uber, but things like pyro airblast can remove threats in close proximity, explosives were the best way to deal with sentries on high ground, around entrances, etc. Short circuit's old firing rate was nice when dealing with active soldier spam or demos in a 1v1 setting, and it generally lost to team-oriented spam with the old firing rate.
Darwin's Danger Shield
-Having low-charged-headshot immunity (surviving with plenty of health to duck around corners or cover) drags out gameplay.
-Playing to charge shots before peaking corners/sightlines is slow-paced and annoying.
Valve announced they didn't want players to have an advantage by owning hats, but the advantage is still prevalent by having the weapon advantage. I can't hope to win a fight against a Darwin's Sniper unless I equip one too, especially if he's on a defensive sightline where he's charged his shot for longer to assure a high-damage shot to pierce the 10% bullet resistance. I would suggest either removing the health buff (or reducing it), so that in a 1v1 scenario, it's still a matter of who shot the head first, rather than a duck-and-cover battle until someone accidentally takes more than 7 damage from other sources.