How to apply sigil and crest to celestial weapon?

[Neone]

Hi there. I've just started to gather the celestial weapons.
Can't get Tidus thou Fought ********* and forgot to obtain the chest, actually, I didn't know about it

Anyway, I've aquiered Rikkus Godhand, the crest and the sigil.
But how to h*ll do I apply to the weapon? I've been trying to apply them through the customise option in the menu, doesn't work.

Searched the forum, but couldn't find any answer, seems like everyone knows how to do except for me :P

The answer for those who doesn't know:

Got a Celestial Weapon? And both of its counterparts, the Crest and Sigil?
Well then make your way to Macalania Woods up the glowing celestial path and
where you found the boy that was looking for his father. Remember that sphere
crystal that changed your Cloudy Mirror to the Celestial Mirror, well, that
crystal like sphere is the key to combining the weapons powers. So go there
every time you have the Celestial Weapon and the Crest and Sigil that goes
with it. I suggest, once you get a Celestial Weapon and a Crest you go there
and combine them because it will exceed an aeon's break damage limit, meaning
they'll do more than 9,999 worth of damage (explained in section 3).