Here is how I would like to do fumbles. If you roll a 1 then you have a potential fumble. Roll the dice again and if you'd have hit on the second roll you just miss your target. If you miss a second time then a critical fumble happens. I'd like to come up with a chart of sorts, but for now I will try to arrange something dramatic. You drop your weapon or it gets stuck, you hit a friend or yourself, you have some other equipment failure, you slip and fall down or something similar. If you have ideas for a fumble chart or ideas to add to mind please put comment below. I'd like to have one with a variety of options so the same thing isn't occuring over and over.
If we also use the Bell curve rule then a possible fumble will be on a 3-5, assuming the attack misses. If a 4 or 5 hits then there is no fumble. 3 always misses and always has the potential for a fumble in combat.