[renowner]

I like the concept, and I would love if this old weapon gets some love.
Personally i'd change the potential skill to require you to have the moonblade effect active, and then it consumes the effect.
The potential skill has a cooldown and otherwise is 150% SWA as you said, and does 1.5x damage at night.

225% SWA total damage at night. . But requires you to land your basic attack first, and then is still a bit weaker than most eclair lacroix. Even without using Eresh.

Or the potential skill could just be, a hit boost at night or something?