The primal longsword is an item that is only available while Dungeoneering. Like all other primal equipment, it cannot be made using the Smithing skill and can only be obtained as a drop from the boss Blink. It requires 99 Attack to wield, and an unofficial requirement of 95 Dungeoneering to encounter Blink. This is the highest level longsword obtainable in Daemonheim, being in the highest tier level for equipment surpassing the promethium longsword.
Marmaros wields a primal longsword during the Fremennik SagaThok It To 'Em, as well as in Thok Your Block Off. However, he uses it as a stabbing weapon in the latter rather than a slashing weapon, although he does use it as a proper slashing weapon when the player controls him in the former.