@ShionSinX
It's all fun and games until the special effect of a floor locks the door behind you and disables any sort of escape skill.
@inuyamato
@Richman
@Riger
@Maho
@gregluck
The better something or someone is at something, the easier it is to edit that thing but the harder it is to reverse it & more exponentially expensive it is to do. I obviously don't have exact numbers to work with, but a shield with a naturally bad skill would take X to remove it completely, but having it reverse and becoming a beneficial skill instead would take X times ten or even a hundred instead of simply being double the cost.
An analogy I just thought up:
Think of a river; we can all agree that a river is very good at quickly moving lots of water from high terrain down to the sea, right?
If we wanted to expand a river or change the direction it flowed in to a straighter path, that wouldn't be too hard to do - anyone with a shovel and enough time + effort could eventually do that, it is fairly easy as it is only helping something that is already naturally good at that thing be a bit better still at it.
If we wanted to dam the river to reclaim the land it was flowing through, you could do that but it would be harder to do than the above because you're trying to prevent the river from doing what it naturally wants to do, this is a medium difficulty task.
If we wanted to make the river flow in the opposite direction and carry seawater up the hill however, that would be almost impossible and at that point you might as well find a different way of doing it like building a pipeline to carry it up, this is bordering on impossible with the difficulty.
Noru's edit / create / bestow skills work in roughly the same manner, the more you go against the natural way of the thing you're changing, the higher the LP cost until it spirals out of control and is either no longer worth it or is impossible to ever afford.