I just managed to hack a cheat device code that lets you customize any equipment ability with just a single potion for each ability.

I have versions of the code for both PAL and American releases, although I can't guarantee the American one works properly (it should do, though). I also can't guarantee it works on anything but Codebreaker version 7 and above, but you're welcome to try (if you're not using Codebreaker or another device that supports raw format codes, you'll need to convert the codes to your cheat device... feel free to ask me if you need help with doing that).

PAL:
40AD4198 007D0002
00012000 00000000

American:
40ADF298 00780002
00012000 00000000