Awakening Sarina & Kana’s version (part 1)
Aster laid down on the floor of Eris's studio whole he caught up his breath, with Rigel's flames as strong as they were now, he shouldn't have needed to exhaust himself to get a good result.
In part he had to thank Ley for "donating" his feathers, he had already done a good part of the work, the maximum possible to integrate was the blood of a Heavenly Conqueror level spirit beast.
As the ones using the "Magistral Wings" manual are those in the mortal realm, but of course when given to a member of the young generation, it has to be refined until its tame enough to not kill its user, then it has to be refined one more time by the one who absorbs it, to eliminate the rough parts before it can be nurtured by the user.
Ley and his family did all that part for Aster and he only had to purify the poisonous attribute which Ley imbued into his feathers, which was a piece of cake for Aster, his spirit energy was stronger than Ley's and Rigel's flames were the bane of any poison.