The M93R is the handgun which is used by Claire in Resident Evil: Code Veronica X. It is more powerful then the Combat Knife but is really no more useful in taking down the bigger stronger based enemies. It is definitely the most useful gun for taking down enemies like zombies and dogs but really useful for nothing else as it doesn't have much power.
The M93R also makes an appearance in Resident Evil 5, where it can be found as its upgraded variant. It is capable of firing 3 continuous bullets.