Wearing any four (or more) of a superior tetsu armour set (including augmented parts) grants a passive ability, Iron Fist, which gives a chance to obtain a ports resource crate when defeating an opponent. The Superior tetsu kote degrade to a broken state after 72,000 charges of combat. They can be repaired by a Repair NPC for 300,000 coins (for a full repair), or for less at an armour stand. Alternatively, they can be repaired using 10 plate (for a full repair) by using them on your anvil in your port.