Board Thread:Questions and Answers/@comment-44935929-20200126205016/@comment-35248429-20200128062114

Remember that divine object weapons in Underworld are created from a memory of what they used to be. When Eugeo merges with his sword the "memory" of Eugeo becomes part of the sword as well.

So he's not alive, he's not coming back. That memory however is going to be import in the finale of war of the underworld, both to bring Kirito back and in the final fight against Gabriel Miller/Subtilizer.