River of Celestial Waters

Karsha shook his head, looking at where his soul weapon had entered. He could tell the sword was devouring the energy there, so he didn't call it back. 

Since they were connected by their soul, even if he left this world, he would still be able to call it back, or it would return on its own. 

Soul items were strange that way—they possessed some sentience, allowing them to make decisions that would benefit them and enable them to grow stronger.

He already knew the sword had room to grow, so he let it devour the chaotic energy coming from the cracks in the ground. 

The sword had already consumed a lot of tribulation lightning but still hadn't leveled up. Now that it had a new source of energy, who was he to deny it? 

Once it had consumed all the Chaos energy in this world, it would return to his soul sea, regardless of where he was.