I was going to suggest sneaking it by. Air Malta has strict carry on policies so I leave the heavy stuff in my car, get the boarding pass, go back to the car (MLA is a small airport), repack and then head on my merry way. They never check weights at the boarding gate. Same thing on their flights out of London except I put my heavy stuff in a baggage locker before getting a boarding pass. 10Kg is just too little allowance.