Final Blade and undead

[Ravenica]

Lich's and Vampires are my problem, will they be finished for good, or will they still get their get out of death free cards? (Obviously if the Vampire is done in during the day it is dead) But will it's soul be trapped? Same for a lich, it's soul is already not present...

[Swivl]

Where would I find this final blade? This is unfamiliar to me.

[Ravenica]

Inner Sea world guide, minor artifact, found in galt, page 300. The line in question irking me is "by passes all DR Excluding epic and negates all regeneration. A creature slain by this effect is immediately targeted by a soul bind effect that automatically places the soul into the blade"

I'm the DM of the game in question so I can fudge it if necessary but I'd like some second opinions.

[Swivl]

As far as my book-flipping and recollection goes these guys still get their options out, mostly because soul bind has no effect on them (the vampire lost the soul entirely and the lich has one but not on the body).

Certainly they would have been valid targets provided they had souls to effect (the target line of "corpse" I can see being ruled either way).

[Drejk]

Lich should be immune to attempts to steal its soul because it is stored in his phylactery.

In case of vampire - soul bind requires that the corpse have to died within last round per caster level. Decapitation does not slay vampire but turns him into mist so he technically he is not a viable target of the soul bind spell.

In both cases there is also a problem that they are technically dead for much longer than 1 round per caster level which is limit of soul bind reach.

Personally, because final blade is a minor artifact, I would make it destroy normal vampires (but not necessarily elders) but unable to capture a lich's soul.