Hi Casey,
I do not have an scientific background, but i have been keeping my N. Wennerae under a 70w pendant for the last month without problem. he still comes out to hunt and explore, so it doesn't seem to be stressing him out too much. i also have a live rock "castle" for him to seek refuge in from the bright light. i believe this helps too.
A little while ago, Dr. Caldwell wrote in a thread that some species of mantis shrimp come from deeper waters and can have health problems from over exposure to intense lighting. i'm not sure if N. Wenn. is one of those species.