Why Dark Reprisal is 2* bomb?
Prototype Rocket Hammer and Fractured Mask of Seerus are both 1* items. According to Patch Notes (February 29, 20129) Dark Reprisal should be 1* as well. Also its damage bar is less then the one of Cold Snap or Firecracker which are both 1* bombs.
Is it a bug?
Also if Dark Reprisal were 1* it could be at least usable in T1 Lockdown (just like those other items available in mission O:CH T1).
Post this in bug reports