It's strange that they finally decided to add the Slayer. I suppose there must of been a lot of demand.
When they first anounced WAR, the slayer was to be the dwarfs DPS class. They then changed it Hammerer, because it kind of fucked up the Lore. Dwarf Slayers are basically suicidal maniacs. Dwarfs can't actually commit suicide (to do so would be a against their nature and a huge dishonour) so when Dwarfs feel like they have been disgraced they take up the mantle of a Slayer, die their beard red, wear next to nothing and they find the biggest and baddest monster out there and fight it. They keep doing this until they are beaten in combat, so that they die but they keep their honour.
To sum it up, I can imagine Slayers would be pretty pissed off with Healers.