It was anti magic. When he first got the sword they made it clear that the sword cuts through magic.

@@poiboi4712 but he still used pure physical strength

@@poiboi4712 reflecting magna's fireball was done with pure physical strength, beating sekke was done with pure physical strength, even now, asta still uses pure physical at times

@@poiboi4712 also, when asta fought raia, mereoleona moved faster than light and asta blitzed her in base form without using anti magic, his physical strength makes it possible for him to move at ftl speeds in base form.

@@daniken2707 defeating seele wasn’t pure strength. Just because at that point you can’t see the anti magic doesn’t mean it wasn’t there. The sword broke through the shield with anti magic and then pure strength knocked out sekke. Without the anti magic he would have lost. Same with magma’s fireball. Asta literally said he didn’t realise the sword could reflect magic aswell. That was kinda the point of the different swords. The first one could grow in size to help reflect magic. The second one could harness magic so that he could use it and the last one could absorb and nullify magic including effects from magic that had already happened.

Maybe I watched, maybe I didn't, and the reactions may not be accurate for you