@Intruvious Like I said, your definition of what constitutes external is completely ambiguous. Consider that Spiderman loses his spider power when his spirit wavers. Or do you have the same gripe with Green Lantern who embodies Iruma's dependency in the ring to an extreme? Real life abilities like athletic, musical, and artistic skills will also fade or become rusty if you don't practice on a daily basis, or could flicker out suddenly when you suffer burnout. ANY power has weaknesses to be exploited, and if you want to play speculation, the worries are endless. The reliability and permanence of a power is so much more complicated than something as arbitrary as being considered "your own", especially since we have no idea just what is capable of taking that ring off Iruma.