Chain Mail +3 is (almost) the best piece of armor for bards. The only better option is killing Drizzt Do'Urden for his Mithral Chain Mail. It can be gained as loot from Baresh when the party returns to Ulgoth's Beard after successfully finding Balduran's Logbook. It offers a +3 armor class bonus and is 31 lbs lighter than normal Chain Mail.