I don't think that he meant "bleed" in a literal sense, though that's what was achieved by the end of the movie. His goal was to prove to Xerxes that he wasn't the immortal ruler of the earth and that he didn't have the right to induce tyranny and war in otherwise peaceful nations.
Pft... that's what they want you to think.
Maybe Xerxes did all the piercings himself, and his people never saw him bleed, so they thought he was invincible. Yeah, that's it.