I've been following this thread for a while and it just occured to me:
Work backwards.
Let me explain -
Think of what weapons you'd like, and intergrate them into the armor. Think Robocop - his gun holster was in his leg.
Perhaps your thigh armor has a knife built into it. It may alter the shape of the armor a bit, but it IS a custom mando. Are you planning on carrying a backpack or cape? You can hide alot in there. Perhaps your belt buckle, , a piece from your gauntlet and a portion of your back armor combine to form a sniper rifle. After a 'mission' you can break them down, attach them to the outfit and walk away.
A number of dress uniforms are not complete without a weapon (usually a sword or small sidearm) of some sort.
I'd decide what weapons you'd want, draw them where you'd want them, then design alot of fancy stuff to conceal them.
Just a thought- Hope it helps.