You can change your party’s equipment in the Equipment menu. There are characters with exclusive weapon types while some share the same equipment type. It's quite convenient for characters to have the same weapon type since you only need to have one of them to level up the Customization skill to craft better weapons. You can also press X to automatically equip the best gear you have in your inventory for that character.
Here's the list of all characters and their weapon types:
* Roddick, Ashlay: Swords
* Millie, Ioshua, Erys: Rods
* Ilia, Pericci: Gauntlets, Knuckles
* Cyuss: Two-handed swords, longswords
* Phia: Daggers, short swords
* Mavelle: Orbs
* Welch: Sticks
* T'nique: Staff, halberd
Take note that your equipment doesn't only provide you stat boosts; you should also consider the elemental properties of weapons. For example, the Silvance is a very powerful sword but has three elements: Light, Dark, and Wind.
While this can pretty much mow down all other enemies, you'll be in deep trouble if you encounter an enemy or boss who can absorb damage from any of those elements. That's why it's recommended to have extra pieces of weaponry, especially neutral ones, so you can easily adjust your strategy if you find yourself struggling with enemies or bosses absorbing your blows and healing them instead.
There are also accessories that have hidden effects and properties. For example, the Ring of Absorption has a very enticing description that converts physical damage inflicted on the wearer into HP. This seems to be overpowered but it doesn't say in the description that this accessory can break (you'll lose it permanently) after absorbing a certain amount of damage.
At the same time, be wary of accessories with impressive effects or boosts. A great number of them have negative effects that you'll need to take into consideration. Like the Ring of Might that doubles the wearer's attack rating but at the same time doubles all incoming elemental damage dealt to your character. Always check the description of your accessories you'll equip, not just the stat boosts they give.