Weapons of the Maruukai

Criteria:
Defeat Teera and Maruuk while holding the Spear of Tolui, War Axe of Berke, and Bow of Sartaq in The Nokhud Offensive on Mythic difficulty.

Strategy:
Around the boss arena, there are caves that hold weapons. Three players must click on the weapon before the boss encounter starts. The spear causes players to take 20% increased damage, the war axe reduces the player’s movement speed by 30%, and the Bow reduces incoming healing effects by 20%. Each debuff lasts for 5 minuets. Once all the weapons are acquired, defeat the boss as normal, and you’re done!

Pro tip: If a player dies, the weapon will be dropped and must be acquired again.

Three weapon in three cave, [spell=392531], [spell=392419] and [spell=392541]. once you take it, you will get 5 min debuff and weapon disappear, but weapons will respawn when debuff expire or player who take the weapon dead.

pic: https://imgur.com/MsqCtzj

You can easily solo this achievement with alts by ALT-F4ing between them.
Being offline doesn't remove the debuff.

Park your main near the spear (closest weapon to boss) and your alts near the others.
Quickly switch between your alts by ALT+F4ing to click their weapon and engage boss with your main to lock your alts in fight.
Pop all CDs and burst the boss to get achievement.
My alts were too far to suffer any damage.

Hope it helps!