I don't even know what you're talking about any more, lol. There's hitstun, hitlag, shieldstun, and shieldlag.
Shielding results in normal shieldlag, followed by sliding while in shieldstun.
Powershielding results in reduced shieldlag, followed by reduced sliding while in shieldstun.
There is no difference for the attacker in terms of hitlag. Hitlag is applied whether the attack hits a person or a shield, and it is equal to the person hit in number of frames, but greater than the number of frames of shieldstun, even normally.
Shieldlag and shieldstun are directly based on the amount of damage that was shielded. Brawl- Ganondorf's Warlock Punch deals 666%, so the effects are hugely exaggerated.