The crowbar is what Moira uses as a melee weapon in Resident Evil: Revelations 2. As one of her primary survival item besides the flashlight, Moira is able to somewhat properly defend herself.
The crowbar found early during Claire Episode One in the abandoned prison facility and goes to Moira. It is used by pressing melee button. Compared to Claire and Barry's knives, the Crowbar is slower but has better reach. It allows Moira to perform follow-up melee attacks when enemies are downed as opposed the knives which can't without a certain Skill. The crowbar allows Moira to use stealth-attacks by approaching enemies from behind while they are not alerted.
Because of its swing arc, the crowbar has a tendency to hit Afflicted in the head with regularly aimed attacks doing extra damage.
As a key item, the crowbar is required to be used (via the interact button) to pry boards off of doors and allow access to areas that Claire and Moira previously couldn't enter.
The "Batter Up" Skill increase the attack power of Moira's crowbar and "Crowbar Finisher" allows BP to be gained by using a follow-up attack.