Alright, thus far I've found pieces of Braccus' armor in these locations:
1) Boots of Braccus Rex: In the secret chamber inside Fort Joy which you visit during Whitemoore's quest. 2) Helmet of Braccus Rex: in the vault with the cursed lever, in the same area where you have to rescue Gareth. 3) Greaves of Braccus Rex: Tower with lightning clouds past the woman that caused your ship to shipwreck, on a corpse. 4) Armor of Braccus Rex: Inside the Illusionist's Vault.
5) Gauntlets of Braccus Rex: where are these?! I suspect they can be found inside Braccus' Laboratory, specifically inside that sarcophagus that couldn't be opened. Can anybody confirm this?