The Aetherneal Bond is speculated to be a Aetherneal spell that is normally used by the Arite family. It is a symmetrical spell that would allow both users to have the same rights. This spell is a permanent spell and cannot be undone unless one of the caster of the bond had died.
It is activated when a Elibu and Argel cast a certain trigger spell with the Argel casting first and Elibu casting very shortly after. The timing is essential in order for the trigger to work. When active, it lets a Argel and Elibu form a bond with each other's soul.
This lets them share their mana pool resulting in them being able to use all magic (aside from Aethernal) without the need for any artifacts. When the bond forms, a evolving tattoo forms on the left hand of the Argel appears. The tattoo of the Argel would be then an indicator of how much the bond has grown by telling how much the tattoo grows. The more the bond grows, the stronger the users would be. The markings of the Elibu would be a danger indicator. The Elibu's marking will shrink when the bond shrinks. It is still unknown what will happen when the bond shrinks but it is labeled to have a dangerous effect.
When the bond forms, the senses of the Argel and Elibu's senses would be enhanced. The Aetherneal Bond changed the Mind's location to now be located where the mark of the Aetherneal Bond was. The mark can sustain the same amount of mana and would not change even if the distance between the users are far apart from each other.
It lets their minds be on the same wavelength allowing telepathy. They could feel each other's Mana and heartbeat. Tested by Kiel Rroda and Elaru Wayvin, their telepathy's effect increases the farther they are from each other. They could even feel each other's emotion and the state of the body including pain and breathing. They could feel each closer, the farther they are. Kiel believed that was the case because the distance increases between them which cause them to lose control of what they send over telepathy.
Due to the linking of the soul, they cannot get too far away from each other or else the tendrils of their souls would stretch and cause damage to their body. Their souls only stay in between them which means if they are far apart from each other, mana had to pass farther to reach the mages.