Does the "Hidden Arm Slide" weapon accessory modify the concealability of a weapon at all? The brief description in the rulebook only discusses drawing the weapon as a free action but doesn't touch on concealability. The "Hidden" part of the name makes me thing it should, but a heavy pistol up the sleeve is pretty noticeable, I would think.
I wouldn't think so, because it doesn't actually make the weapon smaller, or protect it from a scan. It just makes it easier to draw when it's concealed. If it doesn't mention in the book that it affects concealment, it's probably best to assume that it doesn't. The only exception would be that if it's built into a cyberarm, obviously it would be concealed within the cyberarm.