RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Mithril Scimitar
The Old School RuneScape Wiki also has an article on Mithril Scimitar.

A Mithril scimitar is a scimitar that can be made using the smithing skill at level 55 smithing with two mithril bars, yielding 100 smithing experience. They are also sold in the Al Kharid Scimitar shop for 1040gp. Like all mithril weapons, it requires level 20 attack to wield.