Prayer Shawl is a light armor set. When you heal a friendly target, you have a 6% chance to grant them a damage shield that absorbs 2425 damage for 6 seconds.
Prayer Shawl is a beginner healing set that you can obtain quickly and easily since Spindleclutch I is one of the first dungeons you will be able to enter via the Random Dungeon finder tool. It is outclassed by better healing sets; however, the ease with which you can obtain it makes it popular for beginners and as a leveling set. Because the proc chance of the 5-piece set bonus is so low (only 6%), you will have to heal proactively in order to take advantage of it, and even so, 2425 damage is a bit low. However, the 2 to 4-piece set bonuses are very nice (Max Magicka, Spell Damage and Magicka Recovery).
The Prayer Shawl 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 light armor, weapons and jewelry of this set in the Dark Elf motif style.