Covenant chestplate

The Covenant Chestplate is a piece of armour worn on the torso.

It is extremely popular amongst PVPing low-levels due to its unique effect, which scales the strength of the armour to the level of the player using it and the weapon the opposing player is wearing; resulting in a low-level player being able to have a chance at beating a higher-level player if they are using a very powerful weapon such as one of the Godswords, causing the enemy to hit very long strings of 0s. It is the defensive counterpart of the Covenant Longsword.

Trivia
Players were originally able to wear the Covenant Chestplate and wield the Covenant Longsword at the same time, but this was confirmed to be a glitch by Jagex and was rectified the day after the release; it is now possible to wear only one of the two items.