Since brute force didn't work, Jake readily tried another method and it turned out to be the right choice.
Determined, he released the claw from one of his index fingers and directed the Grey Aether from his other claws and fangs to that claw. The claw, which he could now extend up to 20 centimeters thanks to the evolution of his bloodline, now seemed to be wrapped in a ghostly grayish light sheath.
Next, his lava veins and his entire body began to glow with intense heat. Calmly, he concentrated all this heat towards this single claw and very quickly it began to shine as bright as a mini sun.
The radiant heat of his claw was such that his own skin was somewhat itchy just by coming into contact with the heated air. Right now, he wouldn't have dared to touch his own claw without a thick layer of Constitution Aether for protection.
The Soul Spell he just performed is in fact an Aether Spell since he simply manipulates the Aether nearby to reproduce the symbols as if he were performing an incantation. Currently, Jake cannot touch the Aether composing his own soul. He can activate Soul Glyphs for example, but he can't see them, even with his Extrasensory Perception.
Bloodlines follow the same principle with their Aetheric Code, except that it is automated for obvious reasons. With all the preparation and training to form his Aether Core, Jake already has the basics to start learning all sorts of spells, which will nevertheless be like long incantations difficult to maintain in the middle of a fight.
Visualizing thousands of symbols and controlling the Aether so accurately is obviously dependent on mental stats and Spirit Body level and requires training. For a normal human, even with a lifetime of training it would be impossible.