They'd be an incredibly powerful Nephilim because lucifer was a powerful archangel rivaling his brother Michael. It doesn't matter if he's the devil he's not a demon himself just the ruler of them.

This one is a little tricky, since it’s been sad that the devil is actually a demon and others saying that he has actually fallen angel. But to answer the question, if he’s a fallen angel, then the child would be half fallen angel and half human.

I think that in that situation child will be nephilim if not interve in natural process.

Luci is angel source user no matter how not beautiful he uses it.

Also need to notice that all power that have luci is bestowed by his creator and all intellectual rights to edit existence concentrated in god hands and all waroungs can be fixed.

Demon is separate race and devil not been born as demon, even if he fallen he still angel but in different form.

Really & truly Demons & Angels aren't separate species, pop culture has made them into separate beings. More than anything, the title Demon is like being designated as a traitor but a government. So if the Devil was allowed to have kids, they would be a powerful Nephilim because Satan was a Cherubim.

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