Armor 3 in your cyberarm has availability 15.
While for the game there is no rules against it, realistically they are a two handed weapon. Otherwise recoil is to much with the weapon weight.
No, they don't "lose out". They choose one of the three areas of Magician to specialize in, giving up projection in the process. Really, they're better of than a full mage because they have fewer skills they need to invest in.