It does look brand new to me...
I would consider what it would be worth to you as delivered.
Then craft your letter carefully. May take a few letters building up to the final disposition. Lead the seller, convince him he needs to do the right thing and that any PP dispute will cost him cash most likely.
The Snake Plisskin I know would either shoot the guy or work something out and walk away clean. He wouldn't waste time negotiating and then complain about the outcome of the negotiation.
Seriously though, if the seller agrees to an offer, and the Sterff has arrived at a number, why would he still be mad? Worst case; the seller should accept refund w/ no shipping costs incurred to Sterff if Sterff doesn't want w/engravings.
Perhaps leave a star or 2 less re: 'how accurate was the description'. Those can ultimately cost the seller a little money in higher ebay fees (probably that will just be passed on to buyers). Keeps sellers on their toes. If he responds and is reasonable about fixing his horrible listing in a way that leaves Sterff satisfied.