Spectral Hand & Invisibility & the Assassin's Death Attack...

[RigaMortus]

And can even do so through flanking.

No, it specifically says in the Spectral Hand description that you can't flank with it.

However, I wonder if you were flanking a creature (not the hand, but the caster), and cast a melee touch spell through the hand, would you then be able to SA with it?

 

[Bauglir]

No, it specifically says in the Spectral Hand description that you can't flank with it.

However, I wonder if you were flanking a creature (not the hand, but the caster), and cast a melee touch spell through the hand, would you then be able to SA with it?

I'm not sure if by 'cannot flank' it means 'cannot provide flanking' or 'cannot benefit from flanking'. It does after all make a melee attack which is sufficient to benefit from flanking.