The Ashmen Hakars lead the Ashmen in battle. Thanks to Wrath of Kings' rules and army building system they are not attached to the Ashmen in the same way that a Space Marine Sergeant is attached to his squad. Instead they take a role far more in line with that of an Independent Character (which is very much a simplification, but it'll do for now).
The Hakars share the same general body, but are differentiated by their heads and weaponry.
And here's their slightly fuzzy modelling shot. (The mould line on the blade needs dealing with.)
I really like the model on the right, and I think he is my favourite model from the whole of the Starter Box. The left hand model is a different matter, with a mask that runs counter to the aesthetic of the rest of the force, as does his polearm. If I can source the part I am thinking of replacing the blade with a hammer head instead (having seen that conversion done elsewhere on the web (I can't remember where or I'd give due credit).
For my opinion on the sculpts, plastic etc, and to avoid repetition, see the end of my Ashmen post.