AbdulAlhazred
Legend
I am big on the legendary angle... myself
Uther that selfish bastard plunging Excalibur in to the stone and declaring only he and his could draw it forth had a spine tingle to it.
I think it works fine as a MP too in part because I see daemonic, draconic, fae, and divine blood-lines in basically a huge number of heros, villains and kings in legend and even asserted in history. All the main players in Arthurian legend had a special bloodline as does every character the greeks called hero (which literally meant defender btw)
Well, I just see MPs and Rituals as things you LEARN, not things you ARE, but its all just mechanics. Maybe being able to CREATE something like a 'sword in the stone' is a ritual/mp. IIRC in at least many versions of the legend it was Merlin who did that, but there certainly isn't any one canonical version of that story.