I believe it is an honorary name. When our not-so-beloved prince disembowels Angel at the beginning of WC3, he says that not only she has defeated many Kilrathi warriors, but her lairmate is the Heart of the Tiger. The way he says it sounds to me like an effort to explain to the crowd how important Angel is, so it is not the right place to use a derogatory name for Blair. Say whatever you want for Thrakath nar Kiranka (looking at you, Khasra), but he is a good orator.