The legendary armaments is one of the many trophies and achievements within Elden Ring. Getting them all will unlock the trophy achievement.
This specific page is focused on Ruins Greatsword.
WEAPON ARMAMENT: Ruins Greatsword
UNIQUE SKILL: Wave of Destruction
LOCATION: Redmane Castle
In order to get the Ruins Greatsword you will need to travel to Redmane Castle, here you will have to speak with the announcer in order to trigger a teleport to a boss fight with Starscourge Radahn. You can encounter the Starscourge Radahn boss fight through the Ranni the Witch quest, so just follow that quest until you have defeated that boss.
After defeating Starscourge Radahn return to Redmane Castle and speak with Witch-Hunter Jerren, who can be found near the church and the announcer. He will then congratulate you on defeating Radahn.
From there leave and come back to Redmane Castle and there should be some new boss fights appear in the Redmane Castle plaza.
Defeat the new bosses Misbegotten Warrior and the Crucible Knight. The Ruins Greatsword will be a reward for defeating these two bosses.
Originally rubble from a ruin which fell from the sky, this surviving fragment was honed into a weapon. One of the legendary armaments.
The ruin it came from crumbled when struck by a meteorite, as such this weapon harbors its destructive power.
Raise the sword up high, then strike it against the ground to fire off a wave of gravitational force.