The main RuneScape Wiki has an article on: Rune Axe
The Old School RuneScape Wiki also has an article on Rune Axe.

A rune axe (sometimes referred to as a rune hatchet) is an axe which requires level 40 attack to wield. It is the best axe available in RuneScape Classic, and can be made from one runite bar at level 86 smithing, yielding 75 smithing experience.

The only way to to obtain a rune axe is to receive a drop from a monster, to create one with 86 smithing or to trade with another player.

Like all woodcutting axes, it can be used to cut trees by players with any woodcutting level.

Legend's Quest

During the Legend's quest player must use a Rune axe to Chop and trim the Yommi Tree to form a Totem Pole. This means the player must either have a Smithing skill level of 85 (or 84 with the use of a temporary skill boost achieved by consuming a Dwarven stout) to create the axe, or they must acquire it via a drop from a monster, or by trading with another player.

Bonuses

Dropped by

Monster Combat level Quantity Rarity
Black Dragon 200 1 4Rare
Fire Giant 109 1 4Rare
King Black Dragon 245 1 4Rare

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