ff13 weapon upgrade questions.

Which weapons are best for upgrading o.O i don't want to waste a ton of mats and then get something better and throw all this work out the window haha. Is there somehwere i can find a guide for it maybe? Or does anyone just know?

i'm sure there's an FF13 wiki on the net, or you can use gamefaqs. The piggyback guide on this is actually pretty good if you want to spend the $20 or so. You're going to need some kind of comprehensive list that shows the weapon's final stats, special property and synthesis group to make your decision, because in the end, the answer to your question depends on your play style. I'll explain:

Each character has eight base weapons that can be bought in stores or found via a chest. The eighth weapon for each character is actually only purchasable through Gilgamesh Inc, which is a shop you get access to after completing a certain mark (in the faultwarrens, fyi). But each of these eight weapons can be upgraded to that character's ultimate weapon. The path you take to the ultimate weapon (i.e., which of the eight weapons you upgrade to ultimate) affects the ultimate weapon's final stats and inherent bonuses. For example, I used Vanille only in a Saboteur role, so I chose to upgrade her Belladona Wand to the ultimate weapon because the Belladona adds a bonus to debuffing (Sab spells). So which weapon you choose to upgrade depends entirely on how you plan to use that character. For Lightning, I found myself using her equally as Ravager and Commando, so I chose to make the Omega Weapon out of a sword that gave an equal boost to Magic and Strength.

Keep in mind that ultimate weapons will not inherit the synthesis group of the weapon. Basically every item in the game has a synthesis group that it belongs to except for very rare accessories and ultimate weapons. The effect of the synthesis group is that for equipping a certain amount of items from the same group, you get a special bonus. For example, if you have 2 or more items from the Gestalt group, you get the Instant Chain bonus which gives you a random chance of staggering your opponent with a single blow/spell. Fang's Taming Pole counts towards this ability, but if it's upgraded to her ultimate, it will lose it. So don't base your choice for an ultimate weapon on a synthesis group.

Your ultimates should be based on stats and the weapon's special property. This means you might want to have a second tier weapon (one tier below ultimate)around just for tactical purposes. because some of the best abilities only unlock with five equipped items from that group. If you're fighting an enemy that only deals Magic damage, for example, you might want to have a Sentinel equipped with five items from the Magistrel Crest group as having five such items equipped will grant you immunity to magic damage (but you'll be unable to heal the character), making your party nearly invincible for that particular fight.