The Lunar has some clear advantages, is one of the strongest weapons to deal with regular enemies in ng3re.
When you hold heavy attack and release it, (without fully charging ET or UT), you do a hold attack, which is an universal mechanic in ng3re, so far so good. The lunar has the propertie of said attack being fully invincible and i think you can shuriken cancel it, being a completely safe move that also has high priority and high delimb chance. You can do from any non launching heavy attack. (This invincibility property on held heavy attacks is only shared by ayane and momiji besides the lunar staff).
The lunar in general has high delimb properties like it used to in NG2. The 360Y has good crowd control, even more coupled with the spinning shuriken move. The jumping heavy attack has iframes.
And the last but not least advantage of the lunar is that it builds lots of meter, faster than any weapon i think, in both regular attacks and OTs, and all of its UTs set up OTs afterwards, It is a very good weapon to use ninpo constantly in battle.