My internet handle used to be another name, but I was forced to change it after an incident involving some former friends and them cyber bullying me into leaving a website when the staff would do nothing about their behavior despite proof.
I changed it to Sigilmancy because at the time I had been watching an anime that was based around a video game and had the idea of a 'sigilmancer' as a class game players could have. Being very into witchcraft and loving the idea of sigils I found this interesting and delved a little deeper into the more real-world side of this, then decided that if a necromancer practiced necromancy why would it not be sigilmancer to sigilmancy? I liked the sound of sigilmancy (and the shortened form of sig or sigil as a nickname) and decided to keep it as an internet handle from that point on.