There's a sword (blade) with holy weapon and other interesting properties you can get easily in this (2nd) mission, and a more complicated scripted procedure to get an even more potent AoE weapon against the undead, one of the ingredients for which also functions as a "sort of" funny lesser weapon, in addition to several holy water potions, one of which again in a sort of funny side quest.. Exploring is everything in CL. One can also get mutually hostile AIs (Mercedes for instance has a very ...
It's a shame you haven't played Calendra's Legacy first. That's the Source.
In addition to the above recommendations, also interesting puzzle missions (or at least partly including puzzles): King Abedzen's Tomb; Secrets of the Old City; In These Enlightened Times
I see you already played the likes of Beneath the Sands/Whispers in the Desert, Temple of the Tides, Forgotten Tomb and so on
Also one big environment puzzle of a classic mission of an entirely different kind: Thief: Brainchild