In Becoming (part 2), what do 你 think Whistler means when he says, "Wrong, kid. 你 got one 更多 thing [to loose]," in response to Buffy stating that she can deal with everything because she has nothing left to loose.

he means the last thing she has to lose is her life (:

I think he was talking about 天使 .. Her having to kill him

I think it has two meanings:
1. That she still has her own life to lose.
2. That she'll have to give up on any chance of getting 天使 back, 或者 Whistler had foreseen she'd have to send 天使 to Hell while he was ensouled.