Armlet

An Armlet, renamed a Leda's Bracelet in Golden Sun: Dark Dawn, is a Bracelet-class arm equipment available in Golden Sun, The Lost Age, and Dark Dawn. It is sold in armor vendors at Kolima, Xian, and Altin in Golden Sun and at Mikasalla, Naribwe, and Kibombo in The Lost Age. This bracelet can be equipped on all mage-style Adepts in both games, namely Ivan and Mia in the first game, together with Jenna and Sheba in the second. It increases the equipped Adept's base Defense rating by 17 points. Its buy value is 900 coins and its sell value is 675 coins.

In Golden Sun when the Armlet is first buyable in Kolima after the town is restored to normal, it is a very strong purchase because it offers significantly more Defense than anything Ivan and Mia could be wearing at that point, a Leather Armlet and/or Leather Gloves. You would very much want to buy two Armlets in that case.

In The Lost Age, the Armlet is just as much of a useful piece of equipment to buy for the same reasons, only even more extreme: It is sold in Mikasalla, making it sold early enough in the game that when Felix's party first enters the town Jenna and Sheba would only be holding Padded Gloves and/or Leather Armlets. However, because they and other comparatively powerful equipment such as the Psynergy Armor and Bronze Helm are sold so early in the game, you'd be hard-pressed to amass the large amounts of coins necessary to buy everything and would need to fight many random monster battles outside Mikasalla to do so.