Chapter 5, Page 215 to 218
Erice has the ability to synchronize with the evil spirits residing within her, and displayed part of the ability to deal with servants who went out of control. When doing so, blood from her thumbs from both hands will start dripping. Her blood color when doing so will be blackish red.
Erice can utilize the corrupted blood caused by spiritual disease generated from her arm to form a dense, glossy black "branch" looking weapon. In one of the battles, she had her fingertips generate those branch and extend it, piercing a stray servant's inner body to grab their Saint Graph's core. By separating the core away from the servant, the servant will dissipate and can no longer maintain their form, and the "branch" will have the Saint Graph core assimilate with the branch as a part of it. Doing so does not return the servant back to the Throne, but the master who lost the servant will still have their Command Seals recovered and can possibly still summon the same servant, although the same servant summoned will have all their memories wiped clean.