Preferred weapons & fusing
Weapons can also be upgraded, using the scraps that you collect during the missions or as various in-game rewards. But there is a bit more to take into account when it comes to weapons than simply upgrading them as much and as often as possible.
For starters, each Hero has a specific type of favorite weapon: some prefer pistols, some prefer SMGs and so on. This should be taken into consideration and you should always equip your heroes with their favorite type of weapon, as this gives that particular weapon a really nice and useful bonus.
Only when you are sure that you have a hero’s favorite weapon available (ideally the best weapon in that particular category too), you should start investing heavily in upgrading it and using scraps to level it up.
The only exception is, in my opinion, Big Daddy who favors the shotgun which, in most cases, is pretty much useless because it only has a very short range.
Even better, you will soon be able to fuse weapons in order to increase their quality and provide a massive boost to its stats. Most weapons in the game are obtained at C rank, but can be upgraded a few times.
In order to fuse weapons, you will need three identical weapons of the same rank. Fortunately, the level of the weapons doesn’t matter, so there’s no need to level up duplicate ones.
But you might have to fuse a lot and wait even more until you collect the right amount of items to fuse: you will need three B-rank weapons to fuse them into an A-rank, and you will need two A-rank ones to fuse even further.