Astarian is pretty bad ass actually. You separate him, make him sneak to a high ground position, I also gave him the jump spell and he becomes borderline overpowered with backstubs and sneak attacks. Can you seriously replace a rogue in this game with somebody else doing traps and lock picking? I bet you will need to waste some feats or skill points to make it efficient.
A Dex Ranger can be a suitable replacement. Wood elf get the free proficiency in Stealth and if you pick a background with sleight of hands, you got all the bases covered.
