The drygore rapier is a level 90 degradable melee weapon. It is a rare drop from the Kalphite King. To wield this weapon you must have at least level 90 Attack, and it is currently the strongest rapier outside of Daemonheim; also surpassing many 2-handed weapons. The drygore rapier degrades after 10 hours of combat, similar to chaotic weapons.
Drygore weapons degrade with use and can be repaired with chitin scraps which can be gained from breaking down damaged chitin - dropped by all exiled kalphites - on an anvil. One chitin will break down into 20-40 scraps depending on your Smithing level. You need 60 to break down the chitin. It can also be repaired at an Armour stand in a PoH or Bob in Lumbridge for 3,000,000 coins.