Tahir's Weapon is a unique legendary machete that appears in Dying Light. It will be automatically added to the player's inventory after defeating Tahir inside the museum near the end of the story quest The Museum (quest).
Like most other unique weapons, it does not scale to the player's level. Its damage output is on par with weapons at about player level 15.
(Bug) Tahirs weapon will stay in your inventory when entering bozaks horde.