This would differ from your run of the mill frigate or prowler.
It would have:
Faster speed than normal frigates.
Advanced sensor systems. (fleet buff).
Powerful but slow to recharge belly slung weapons systems.
Good point defense systems.
Possibly Spartan Boarding teams.
The role of this frigate would be to act as small nimble vessels that can dodge through defenses and cause some damage to supply lines similar to the U boats of WW2 acting in wolf packs
.Low in crew cost but these types of frigates have a long construction time and an extremely high price.
It would have a somewhat shark like appearance, somewhat similar to the Normandy. (not that i dislike the UNSC prowlers but they just appeared a bit to "flat" for my liking)
![Posted Image](http://images2.wikia.nocookie.net/__cb20120412031326/masseffect/images/9/96/Normandy_SR2_Alliance_Livery.png)