I think this would be a great combo with the medigun from SVDL, the Portable Fort is it called?
What about:
- A fast projectile with straight trajectory (probably like a lazer beam).. I don't know the numbers for speed :D
-Each shot consumes 5% of uberchage
-Damage taken when active increased by 15%
-And firing speed 50% faster than Crusader's Crossbow