Not mot much to go in depth about here, to start. It's entirely based on how the sword reacts to the Zoni fusion ability. When fusing items into the Master Sword, the item is absorbed; not just visually, but Pelison can't find anything to pull apart. Then there's the runes that appear on the blade.
Image link for reference:
www.reddit.com
![does-anyone-know-what-it-says-on-the-master-sword-v0-ums8d50r426b1.jpg does-anyone-know-what-it-says-on-the-master-sword-v0-ums8d50r426b1.jpg](https://www.zeldadungeon.net/forum/data/attachments/45/45921-4dc9c7a0fbcc2fd80dc9e11fd585c95d.jpg)
As an aside, the reddit does ask a good question, as well. Do we know what the glowing runes say?
Image link for reference:
Reddit - Dive into anything
![www.reddit.com](https://www.redditstatic.com/shreddit/assets/favicon/64x64.png)
![does-anyone-know-what-it-says-on-the-master-sword-v0-ums8d50r426b1.jpg does-anyone-know-what-it-says-on-the-master-sword-v0-ums8d50r426b1.jpg](https://www.zeldadungeon.net/forum/data/attachments/45/45921-4dc9c7a0fbcc2fd80dc9e11fd585c95d.jpg)
As an aside, the reddit does ask a good question, as well. Do we know what the glowing runes say?