The corrupt Ether bullet that one soldier with strange bones has created is not a normal ether corruption bullet.
The soldier with black bones is a void master, just like Neil himself.
What he has done is take an ether storm, turn its rotational direction inwards, making it into ouroboros. Over time, the storm reduced in size, increased in ether concentration.
Perhaps the soldier intended to lock the ether storm within the land token. Land tokens contain ether to be applied in a certain location. It is the perfect vessel to hold a dangerous ether storm. Over time, the soldier could modify other properties of land token, such as the area where the ether storm is applied, turning it into a lethal weapon.
Just like Ouroboros's eating direction could be turned inwards, it's eating direction could be turned outwards as well. When it's inwards, the storm shrinks, when it's outwards, the storm expands.