In order to put Triple AP on your weapons, you need Wings of Discovery. These seem to be rather rare, with the only ones you can get in bulk being from the Chocobo race at Remiem Temple, which is a one-time reward. Checking my strategy guide, it seems you can bribe Marlboros for a few more, but you need a half million gil per monster, and that nets you a whole four or so. Which means I'd need somewhere in the vicinty of six million gil to get enough for a single Triple AP weapon. There's gotta be an easier way to do this! Is there?
If your goal is to get Triple AP weapons, Foo is right - farming One-Eye is the way forwards - that's likely to be way quicker (and cheaper) than farming Wings...
If you do want to go the farming route, your options are:
- Kill (or overkill Shinryu) to get 1 (or 2) Wings. You'll be able to find strategies on how to do that if you search around online.
- Bribe Malboros (540k, 4 Wings)
- Bribe Greater Malboros (1.28M, 8 Wings - not as good value, so I'd stick to regular Malboros if you want to do this).
Hope that helps!