As for it making them soulbound by changing sigils, we have the karka accessory that remains account bound when a jewel is put into it, code is there.
this ^
Also, i’m totally supporting the idea on making them “account bound” and it should have been designed like this since start to me.
Gifts to create legendaries were mades “account bound” and all of their recipes too for a good reason : Having other chars/alt will greatly help your grind during a legendary fabrication, so why we couldn’t use our hard and long awaited reward on them also?
On a personal note, i’m one step (Dawn) away from my Sunrise :p and i would love the idea to be able of using it on other characters of my account one day.