Well, it's already out in America. (Though I don't know when the release date is for the rest of the world.) I've already maxed out everyone and done all the optional stuff :P
Yang's ultimate weapon? Do you mean after you get him back? Well, there's one in the Cave of Trials, one in a shop in the Lunar Ruins, and his Lunar Trial weapon. (Least to greatest, in that order.) Of course, you he can equip two claws, so you may want to equip his 'Hand of the Gods' and the other ultimate weapon he has for great attack power.
Note: For whatever reason, Yang's HP will stop growing normally when it hits 6,009. I wonder why...Meh. Cid's HP will be at 9,999 before level 99
