At her “youth”, Erzulie created a rule amongst Alluvien that every one, mortal or lwa or inbetween, can be killed by a weapon to their heart.

Hearts are often said to be the same thing as ones soul, or at the very least; they are connected/bound therefore one in the same.

Mortal humans and animals will simply die when a weapon is stabbed into their heart, and if they are “revived,” it is only their body left with no heart/soul. They are [[Undead]].

When Gods / Lwa are stabbed in the heart, they are not literally "killed," as they are “immortal.” But they do lose their identity and forms, and ability to even think, and it becomes incredibly difficult if not impossible for them to bring theirselves back to existence. Think of it like "i think therefore i am;" they lose that.

Because of the association of Erzulie making this rule, and using her own created sword, her symbol is known as a sword in a heart, when not just a heart.

This is inspired by haitain vodou as Erzulie’s symbol is literally either a heart or a heart with swords in it.