In Final Fantasy XIII, which weapons/accessories are worth upgrading? Also is it better to dismantle or sell?

If you want to earn the trophy for holding every weapon / accessory you need to upgrade nearly all of them. Dismantling however is almost always a bad idea. If you're just looking for sheer power, upgrading is never actually necessary. You can rely on your crystarium.

Check source for a great guide.

If you love RPGs, then I'm assuming you either love, the strategy, the story, or the exploration. You can find two of these in FF XIII. The strategy isn't anything special, besides equipping items and levelling up your characters outside of battle and planning your attacks wisely during boss battles. Battles with regular enemies usually consist of coninuously pressing the Auto-Battle button. The battles are filled with action, which will keep you entertained for most of the beginning of the game, but gets old eventually. The story is what makes the game. There is tons of character development throughout the entire game, which gives you a real connection to the characters and leaves you hoping they reach success. The story itself consists of multiple plot-points; the struggle of the characters, the struggle of the world around, and all ofthat branching into even more. I've seen some people say this is too hard to keep track of, but for me, it just means more revelations as the story goes on. This is probably one of my favorite stories out of all of the FF games, although others would say differently. The Exploration kind of ruins the game. There is little to do besides run where the games path leads you until you get into a battle or you reach a key point where the story will be continued. For me, it's worth a bit of waiting to find out what happens next and that keeps me going through the "linearity" as it is often described. The design of the word can also keep you entertained. It's beautiful and detailed, and combined with the amazing graphics, you'll find yourself stopping and spinning the camera in circles to see everything. I would recommend buying it, but whether you do is up to you. Are you willing to put up with a few minutes of hallways for hours of an engaging story that you may not understand? As for the other Final Fantasy XIII; there is a XIII-2, but it's another subject entirely.

it depends on what you want your party to do, for example, my party is Fang/Lightning/Hope. i use Fang as my "***-kicker" so for her I upgraded the Taming Pole, i think it's the second strongest(Dragoon Spear is the strongest but i didnt use it because it has 0 Magic) it has stagger lock which you cant stagger an enemy but that's where Lightning comes in, for her I upgraded Lionheart which gives quick stagger, and Hope's Otshirvani gives syphon boost which when an enemy is staggered he starts to speed up his attacks. My advice would be to figure out the abilities of each weapon and see which one suits your preference. I would upgrade weapons before upgrading accessories and as for dismantling and selling well I don't know if one is better than the other, sell if you need money and if you need things to help upgrade your weapons dismantle, so i guess a combination of both.

here's the weapons list

http://www.ps3trophies.org/forum/final-fantasy-xii...

hm...when I was where you are at, I was upgrading all my first base weapons that the characters start out w/...except Hope (Level up Hawkeye). Once you completely upgrade them, you'll be able to transform them into better and stronger weapons. For Accessories...don't upgrade them yet, you'll get better ones later, for your magic and strength, and HP. Wait till you get the Power Glove, of Sorcerer's Mark...then transform them into better Accessories. Yeah! But not now unless if you really are in need of being strong because you might be too weak.