I haven't come across whatever it is you guys are talking about.
The most efficient way to upgrade weapons is to use 36 Vibrant Oozes to get the x3 multiplier, then buy an Ultracompact Reactor (costs 50,000) and it will usually give 50 and it will give you the most CP for your buck. Takes 2 or 3 to bring a tier 2 weapon to * level, it's not really worth using on the first tier.
Also once you reach chapter 11 you can ride around on the chocobo to find components in the ground, either catalysts or things to sell, and you can also try farming platinum ingots which sell for 150k and the same enemies also drop the catalyst you need for the tier 3 weapons.
Vanille and Fang? Odin is Lightning and Hope.You need to beat him by debuffing him. When he's attacking you Fang should go setinel and Vanille go healer. When he stops attacking and rests have them both go sabotuer, rinse and repeat. I had a shit load of trouble until I did it like that, then it was pretty much cake.