1 Adamantine
4 Dragon Fangs
12 Pulse Ammo
Adamantine: Fight Adamantoises on the beach near Dollet at L30+. Don’t Mug them, just kill them normally, and they should drop Adamantines every time. Also, try Long Horn Island which is near Dollet if you can’t find any Adamantoises near Dollet. If you still can’t find any (they are rare enemies), then refine one of the brothers cards (I can’t remember which one) into 10 Adamantines with Card Mod. You can also mug one from BGH251F2 in FH.
Dragon Fang: Dropped by Blue Dragons. These can be found in snowy forests on the Trabia continent, or on the Island Closest To Hell. Again, don’t mug. They may drop Dragon Fangs, Dragon Skins or Fury Fragments; you only need Dragon Fangs so keep fighting until they drop those, they are quite easy to get. L20-30 T-Rexaurs also drop Dragon Fangs after battle occasionally.
Pulse Ammo: You can only get this by refining items using the ability Ammo-RF. The easiest way is refining Energy Crystals. Late on in disc 3, it is very easy to get hold of these, if you haven’t made it that far yet don’t read. ๐ Once Esthar is full of monsters, go in from the main entrance; go left, left, and up (away from you). You should now be in a screen with a path going to the right, and a path going straight on. Go right, and there is a man standing there. Talk to him; he will laugh, then you have to fight an Elnoyle. Again, kill this without mugging, and it should drop 2-3 Energy Crystals at L40+. It keeps reappearing every time you leave the screen and come back, so getting Energy Crystals is easy. ๐
If you don’t want to wait until the end of Disc3 to get those NRJ Crystals, you can obtain them from Ruby Dragons, who roam in Cetra area, Almaj Mountains to be precise. You can get there as soon as the Balamb Garden is capable of moving. All you need is that your characters are at sufficient level, above 50 in general, and the Rubys will drop them, they, as far as I know, can’t be mugged. Use Tonberry’s Level Up ability if needed.
True, that the most easiest way to obtain them are in, as Meltigemini said, at the end of Disc3. This is still less time consuming than obtaining those Crystals via intense card gaming :]>
Oh, and you don’t need Weapons Monthlys to have those upgrades, if you have material needed you can upgrade any time you want. (absolutely verified).