Maybe for Lone Wolf mages, or maybe if you turn in some of the useless Talent points to the demon to get attribute points.
I don't really think it's that great an idea. You would need to invest heavily into Man-At-Arms to actually make some use out of those Talents, and that means trading in Talent points to get the ability points to spend.
Also you are wrong about the effects not requiring high strength. the basic Divine Light wants 8 STR (30% penalty at 5 STR), and Lower resistances wants 10 STR (50% penalty at 5 STR), and that's just to get rid of the fumble penalty. Mages can't really afford 10 STR.
I don't see that working out terribly well for a pure mage. Maybe if you make a battlemage.