Man do I hate that Chocobo race! grrr!!!

[Shiva_]

Is there a weapon I can invent that will automatically give the Aeons Break Damage limit??

You can't customize one.

First, you have to get the Celestial Mirror. Then you have to get the correct Celestial Weapons and the correct Crests for them. Then you need to activate them (with just the Crest) using the mirror. Depending on which character's weapon you activate, that corresponding Aeon will receive the Break Damage Limit ability. You don't have to have the weapon equipped on the character for the Aeon to have Break Damage Limit.

Here's a list of each character, his/her celestial weapon & crest, and which Aeon will have Break Damage Limit from activating it with the Crest.

Character | Weapon -> Crest | Aeon
_____________________________
Lulu | Onion Knight -> Venus Crest | Shiva
Yuna | Nirvana -> Moon Crest | Valefor
Kamahri | Spirit Lance -> Saturn Crest | Ixion
Wakka | World Champion -> Jupiter Crest | Ifrit

Rest of the Aeons already have Break Damage Limit.