Why not make a sword? You could cut people up with it and deflect flashbangs/SG/HE nades (using the side of the sword not the sharp part of course ). It would be like an Über-Knife. the disadvantage would be that its close range. (if thats too cheap then make it so you cant get guns while u have it).
The differences between this and the knife are:
1) The deflect thing
2) The sword has longer range then a knife
This weapon shouldn't be too expensive, maybe 2-3 credits.