Mom, can we have Moonlight Greatsword?
No, we already have Moonlight Greatsword at home.
Moonlight Greatsword at home:

You were at my side all along

See this faint glow? It's not magic power. It's the glow of insanity, for it reflects it's creator's mad quest to become truly eternal.

Something to keep in mind is that enemies in the DLC resist ranged attacks (flat 50%) not magic damage per se. So if you are thinking about enchanting this for the DLC, you might still get more damage out of magic +5.

Spectacular SL1 weapon with DLC shield and strength ring. More AR than the zweihander when infused raw.

My favorite thing to do is to get 14str,10 dex, spend everything else in 32 adp(for the optimum rolls) and vig/end split. The only downside is the durability, which I get the ring for asap

If you kill Benhart right after you inherit his Greatsword, you get a dupe. Pretty cool for powerstances.