post #241 of 241
Holy water was used in the episode where Giles weakens Buffy somehow and locks her in a house with the vampire. It's kind of a watcher's council test of some sort. She's weak and can't fight the vamp, but somehow manages to trick him into drinking the holy water, and he dusts.

It was also used in an Angel episode where Angel's fighting for Darla to recover and has to reach into a basin of holy water.