I am going to take this space to point out that unless you are playing in a missions legal event, you are free to change the rules in anyway you choose for your home games.
But yes, the general accepted convention is anything that seperates your fist from contact with your target WILL STOP the use of many adept attack powers.
It is your body that is magical, not the brass knucks, not the lead lined glove, not the shock glove, your bare, unmodified hand.
The fact that you use the unarmed skill for many of these weapons relates how the weapon is used. They all use a punching motion exactly the same as throwing a punch. Where as axe, sword, knife, and blunt combat all revolve around how well you can use the weapo (and thus the various 'armed' combat skills.
In short: just cause bare-handed combat and combat with brass knuckles use the same skill and motions for attack DOES NOT mean both are 'unarmed' attacks.