The Arms of Relequen is a medium armor set. Your Light and Heavy attacks apply a stack of harmful winds to your target for 5 seconds. Harmful winds deal 200 Physical Damage every 1 second. 20 stacks max.
If you multiply 200*20 you end up with 4000 damage. This damage can also once again be increased with the Mighty Champion Points perk that increases Physical Damage, or Thaumaturge which increases damage over time. The Tooltip damage will not increase, but the actual damage you do when you put points into Thaumaturge will increase. If you put points into Master-at-Arms, the Tooltip damage will increase, but the actual damage not. On top of that you can also amplify the damage with percentage modifiers from things like Minor or Major Slayer. This can also very easily be activated with bow light attacks, thus making it very good for both ranged and melee setups.
Arms of Relequen comes in 2 versions, an imperfect and a perfect version. The perfect version is slightly stronger in terms of stats than the imperfect version (additional Stamina bonus). The 5-piece bonus otherwise does the same thing on both versions.
Arms of Relequen is part of the Summerset Chapter. It drops in the Cloudrest Mini-Trial in Summerset. Each set item is bond on pickup. You can acquire medium armor, weapons, and jewelry of this set in the Welkynar motif style.