So like, is she a demon too now? or did he just take her soul or smthin?

I guess by saying to take her hands more to somehow makes her as his mate/wife etc (okay i dont know what imma saying)

It was like a man ask his girl to take his hand (as he offer a 'do you want to marry me?) or somethin like dat, perhaps

Okay i take it seriously over a manga. Just ignore this i-have-no-life nanny (〜￣△￣)〜

it is a little like the futurama episode when fry trades his hands for the roboter devil's hands and writes this wonderful opera for leela, who for her hearing made a pact with the roboter devil and gave her hand....