Fair enough on fencing grace.
As far as thoughts on where you could go from your idea of mixing Warpriest and Shadowdancer, these would be my suggestions:
May want to consider going to Warpriest 6 - you get BAB, saves, casting increases and a feat for taking the additional level
One of the Warpriest archetypes with sneak attack will cause issues because you give up your bonus feat which you don't currently have enough feats to afford doing. The other archetype with sneak attack may work fairly well for a character like this, but would require a diety switch. It would also make sawtooth sabers an easy option which do work with slashing grace and makes two-weapon fighting viable.