He is testing hans the whole time... unsure of who he is.
He asks him his name.. to check it against the conveniently placed office number/ nameplate... a test Hans passes.
He offers Hans a german cigarette out of the pack he took off the last dead guy.... Hans takes it and says nothing about it being a german cigarette (most smokers would look to see what someone was offering and if it was coming out of a pack they had never seen before, would most likely ask what they were. Since Hans is german, its just a regular brand cig for him).... test failed....or inconclusive at best.
Since he still didnt know who Hans was he hands him the gun (unloaded) as the final test.
Thats how I see the scene.
Pro Mod Suzuki