Beyond actually just strangling him with the noose, which is absurdly easy? Sword of the Cross, actually just get the noose off of him, the Sacred Guardian custom power. If you can actually just get him to show up to an ambush, that's most of the work done already.
Also, I'd be leery of destroying the Blackened Denarü. I think there was a WoJ or something that said that any of the Fallen getting out of their prisons, either in Hell or in pocket change, would be really really bad. Apocalyptically bad.
If you want to destroy the Noose or just get him to agree to a meeting not under the Accords, that's worth a couple of sessions. Getting an Unraveling might be a few sessions or it might be a whole, if brief, campaign. Creating circumstances forcing Nicodemus to show up to a meeting where he doesn't dictate the terms would probably be a lot harder, because he's really freaking crafty, has two thousand years of personal experience and countless billions of secondhand experience via Anduriel. Maybe go gunning for Tessa, and then force him to show up to an exchange of the coins?