As well as 

"Weapon X:  +20% damage"

"Mech Y: + 20% shield"

What if we had modifiers like 

"Weapon type X: -20% damage" or 

"Weapon type Y: Reload + 2 seconds " or 

Mech Class Z: "- 10% speed"

It would encourage people to try other playstyles.... or... the flow of a game would change a bit and that could be interesting :)