So, I think a lot of players MUST have this issue, because I know I did.
In sieges, you often have to switch from using a gun to using your sword, and there are different mouse sensitivities optimized for these things. In general, you want higher sensitivity when using a sword and lower sensitivity when using a gun... however it's completely impossible to go into your settings and lower or raise your sensitivity tactically in combat when you have to switch to ranged or melee combat.
My suggestion is that when someone is holding a sword or a gun at ease (not aimed) should have normal sensitivity, but when you AIM the gun, your sensitivity is lowered. I would suggest that different guns have different sensitivity changes, like a machine gun would have a slight lowering in sensitivity, a rifle a medium drop, and a sniper rifle a significant drop in sensitivity. Pistols should remain the same.
This is all so that people who prefer using guns in combat are able to aim better without having to go into one's settings to change the sensitivity and put oneself in a vulnerable position.