Draw enemies down on him
Terrifyingly, Burglars can tank quite well for about a minute, but this is a really short term solution whilst the main tank is healed. After their Mortal gold run out and their massive variety of stuns and debuffs are used, all their skills take a long time to cool down, so then they are pretty much dead. This illustrates their survivability, often a Burglar will be the last man standing, being unable to aggro enough to draw enemies down on him.