[........Hm. There's a prolonged silence as Eustace deliberates how much to say.]

...I can't give the specifics, but it has its own system to generate the lightning.

[Probably way too vague of an energy.]

However in Avalon I had to have it modified so that it could use my own magic power instead as its original functions have been disabled. Thus it now relies on me and my own abilities in how fast and powerful it can charge up the magic necessary.