Knightmare is a heavy armor set. When you deal melee damage, you have a 20% chance to apply Minor Maim to all enemies within 8 meters of you for 5 seconds, reducing their damage done by 15%.
The Knightmare set is part of the base game. It drops in Spindleclutch I and Spindleclutch II in Glenumbra. Each set item is bound on pickup. You can acquire heavy armor, weapons and jewelry of this set in the Wood Elf motif style.
ESO Sets