part of the way his power works. he can fire energy, make energy swords, or bounce around in mirrors or whatever and has a great travel speed (and that's just about the only time he ever gets to go at what people generally mean when they say 'light speed'), but in terms of physically attacking someone he can't do it in his light state. hell i don't think he can attack at all in his light state period.
and yes, it does mean he's never really ever fighting at light speed, but that was known already just by the way everyone in one piece is. i mean he's still plenty fast as really just from the speed he can go at almost any hit is pretty strong, but he's probably the slowest 'light speed' guy you'll find.
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The future must protect the clone's past.
"Maybe it's a tentacle, molesting the planet itself. - Aschen Brodel.