nah it would be to powerful if you just allowed them to enfeeble a mob by making a skillchain. If you did that then SAM's would have the potential to land any enfeeble on a mob through their ability to create a lv 3 SC.
What could work though in terms of enfeebles is when a SC is created, an enfeeble that may sometimes be resistant to the mob will land regardless of it's elemental alignment. It would defiantly help with cases in abyssea where you can't land certain magic weaknesses because the mosnter can resist the enfeeble and create another strategic use for SC in general.