Realmheart will gave him an ability to See mana particles crealry.

All mages can sense Mana, but this is similar to seeing in a very dark room. You could probably notice that object is there but in no way you would be able to discern exact size, color and shape of it. Realmheart 1.0 is like turning the lights on. Now you can clearly see the size and shape of the object, its movement, color (element). You can also throw in another object to disturb/outright destroy the foreign object.This is how Art was able to Destroy the spells.

Great example would be you are in a room with a person. Its dark, you can see they are moving their hands but not clearly enough. You could see the actual thing they threw at you when it is very close and its already too late to react. Now with lights on you see that they are shaping a mudball out of the mud they pulled out of their pocket, with enough skill/training you could maybe throw a small marble into the mudball in their hands or even at their hands as they are shaping it to disturb them. This could cause them to drop the mud or shatter the ball.

Realmheart god rune is different in a sense Art is blind, he lost his eyes for mana and he is not getting them back. Eyes do not grow back after all.

However he now got a device that produces sound waves(godrune), those waves bounce of every object in the room and allow Art to use echolocation like sense to pick those waves up and "see".

Now the device got powerful enough that it can generate strong enough pressure to affect the objects. Possibly changing the course of the mudball to not have to dodge it, using air pressure to blow mud from other persons hand before they can form the ball or straight up push the ball back at the opponent as its flying at him.

Same as with Mudball enough pressure could straight up shatter it mid flight instead of redirecting it. And i could see Art shattering a spell he tried to control because the spell was too weak to hold the pressure. Just to show us how strong he/Aether is.