Neshar is more so based off of Guild Wars's Thieves rather than DnD. Those guys aren't tanks, but they are squishy, and they are damned horrible to have against you. And a nightmare when they are working with another player.
As for DnD, he's like a Shadow Dancer, Fighter, and Monk all in one. Which is kinda a decent trade off for having no aggressive spells or powerful magic like the rest of the party. Hes probably far less resilient than Xavier, but has an evasiveness of a ghost.