I agree with your analysis of Z, but I liked Shandra. I thought her character arc was great - much better than say, Neeshka who's character never really progressed in any fashion even after completing Lendon's quest. Shandra went from being a haughty isolationist who refused to depend on others, to a state of confusion and introspection as she apprenticed under you, to finally being a strong-willed and loyal heroine with her own sense of understanding about morality and self-sacrifice.
And that's not mentioning that she pretty became one of the best melee specialists in the group. In fact, after her loss post act 2 (combined with Kelghar being moked and by extension being screwed over), I had to change tactics as the only recognized go-to-guy was Casavir.
But yes, Z's philosophical overtures did come across as a shallow emulation of Dak'kon's. Way too much rambling on and on. She also lacked the underlying depth and motivation needed to enter the Shard Bearer's service and she essentially became his slave - something Zerths and Giths are supposed to take aversion to.