Rae'shalare Feat of Strength - Upgrade Sylvanas' Legendary Bow to Heroic and Mythic Difficulty
The legendary bow dropping from Sylvanas Windrunner's encounter in the Sanctum of Domination has received a few updates this PTR build. Players will now earn a Feat of Strength achievement for obtaining Rae'shalare, Death's Whisper, and two new items allow players who obtain the bow on lower difficulties to increase its item level to 246 and 259, equivalent to Heroic and Mythic difficulty.
Unlike most legendaries, which are upgraded via the Runecarver, the item level of Rae'shalare, Death's Whisper matches that of the difficulty in which it drops, meaning players can get it anywhere from 220 to 259. Presumably as rare as other raid drop legendaries, there are now new upgrade items which allow players to increase its item level to higher difficulties, alleviating the need to farm the legendary again on Heroic or Mythic difficulty. Although Wraithwisp Sinew and Ethereal Fletching are not listed in the dungeon journal, they are almost certainly dropped by Sylvanas Windrunner, and probably won't be as rare as the bow itself, most likely guaranteed drops for players who already own the bow.
Interestingly, only two upgrade items have been found so far, with Wraithwisp Sinew taking the bow to Heroic and Ethereal Fletching upgrading it to Mythic difficulty, with seemingly no LFR -> Normal item level upgrade. Although the item may be added in later, but it's also possible that the bow isn't actually obtainable on LFR difficulty, despite currently being listed in the dungeon journal - previous raid boss drop legendaries such as Aman'Thul's Vision similarly did not drop on LFR difficulty.