*PSST!* Hey, Deku? This isn’t the final battle.

Sure, attacking Shigaraki at 100% is your only option right now, but the war’s not gonna end here. Better hope Eri has enough power and training to heal your limbs. Or, maybe, one of the OFA Users has some kind of healing quirk. Nothing to make you immune to using 100% without being ready, of course. That would defeat the purpose of your training. I’m talking just a little something that keeps your arms from turning into banana pudding.
Speaking of past One For All Users, what’s up with the 4th? What exactly did he do that’s keeping Toshinori from giving Deku the full story on him? My Hero fans on the internet have already noticed the 4th is the only User who doesn’t look all that beat up when he was passing his power. See:

So, what happened? Could Toshinori’s line about not only the wicked seeking power be a clue? Could the 4th had gone in a different direction than simply trying to overpower All For One? Actually, an Evil Overlord beatdown wouldn’t work at all since he’s just the 4th User and I doubt the One For All quirk was even half as strong as it is now. So, maybe the 4th sought out power through other means. Maybe he tried taking over the underworld himself or tried building an army. Maybe…he joined an army to help him accomplish his goal. A…Liberation Army?