"Simple flick of the wrist" would definitely indicate an Incidental. I liken it to the Cybernetic Weapon: it's well-hidden until you need it, at which point (like any wrist-worn weapon) it is suddenly and readily accessible.

If you're not convinced, you can ask the Devs rules questions. But the wording there indicates an incidental.

I´ve sent an Email to Dave 2 weeks ago, but got no answer yet.

One of my players have a pair of Vamblades, and I'm running them pretty much the same way as a wrist-mounted blaster. And according to Sam Stewart, those things are considered "always drawn" for purposes of preparing them. Now obviously, if he's carrying something big in both hands he can't very well stab someone with a Vamblade, but apart from that I just let him slash away. It's not like it's a gamebreaking issue.