Is it? I can recap to try and make it less complex.
The elf licht is born with sword magic, then Licht Dies and his sword magic grimoire is used to seal liebe a demon who wields anti-magic making asta’s anti-magic infused sword magic.
This is the answer to your question and while I could go in more detail we’d then be talking about black clover lore as a whole and not the question that was asked. However if you did want the extra details I’d be happy to provide them to the best of my abilities and knowledge