Presence concealment too high. King Hassan has normal A Rank. You're saying this Hassan has a better hiding skill than the OG. Further more PC drops much more drastically when activated than just a simple + or two down.

Eye of Mind False is excessive. Eye of the Mind (False) B is Heracle's rank. Emiya Archer's rank of Mind's eye true is B. You have a better combative mind then a berserking demi-god, and a counter force agent?

Art of the mind is somewhat lore breaking but it isn't something I would count against it entirely. 

I would honestly just pick a different canon assassin, or go back to the drawing board. Maybe its just that his initial skills are leaving a bad taste in my mouth. 

Okita Souji (in assassin form), or a debuffed Shuten-Douji (Bone Collector for example is a bit vague) would be my pick out of canon servants but others like Mitsuhide Akechi, or Spring Heeled Jack seem like good servants.