you didn't specify what help you needed, but i'll give some help anyway....
how do you get it?
put in GODHAND (all capitals) as a password on the airship and then walk till you reach a treasure chest. you need the celestial mrrior to get it.
how do you power it up?
you power it up with crests and sigils. you go to the place where you power up the cloudy mirror and then you use the crest and sigil.
how do you get the crest?
on bikanel, in a treasure chest.
how do you get the sigil?
you have to go the cactuar sidequest. it takes a while to explain, go here (
http://www.finalfantasy-10.cjb.net/). enter the site and go to secrets and second from the bottom shows how to get it.