To obtain use Luigi's diary on shiny sword .
You can use cosmic diary on it to get cosmic Luigi. :) (don't recommend because luigi is rarer)
Shiny Sword could be bought by 100k on the shop.
E - Barrage
While holding E Luigi does a barrage doing 14 damage.
R - Stun Punch
Luigi punch the opponent doing 35 damage.
U - Heal
Luigi punches who ever is in front healing them for 100 hp.
B + U - Self Heal
Luigi punches the user healing themselves for 1.000.000 hp.
V - Return to Luigi
Any damage that is inflicted on you will be reflected to the attacker. This doesn't apply to Over Heaven stands.
C - Teleport
Luigi teleports you on a short distance without any cooldown.
From Trello here:https://trello.com/c/U8YU90Io/54-luigi