Rainbow
From Chrono Compendium
Chrono Trigger
Used by: Crono
Type: Sword
Attack: 220
Stat Increase: 122
Effects: 70% critical hit rate
How to obtain:
Speak to Melchior after completing the Sun Stone sidequest and Rainbow Shell sidequest to have him forge the Rainbow, Crono's ultimate weapon.
From: Weapons (Chrono Trigger)