with most airlines you have to be able to lift hand luggage into the overheads. The weight limit is set, for one reason, at least, because if a bag falls from the overhead, it will hurt someone very badly- You are proposing to carry 50% more than the allowance and it could impact on others who want to take cabin bags.

Airlines weigh cabin baggage primarily for two reasons: flight safety and operational revenue. From a safety perspective, every aircraft has a maximum takeoff weight and a specific "center of gravity" that must be maintained for stable flight. While small individual bags may seem insignificant, the cumulative weight of 200 carry-on bags can equal several hundred kilograms, which impacts fuel consumption and performance calculations. Furthermore, overhead bins have weight limits; an overstuffed bag could cause the bin to fail during turbulence, posing a serious injury risk to passengers. From a business standpoint, many low-cost carriers use strict weight limits (often 7kg or 10kg) to encourage passengers to pay for checked luggage. By enforcing these limits at the gate, airlines can manage cabin clutter and ensure that boarding processes remain efficient, as there is limited physical space in the overhead compartments. Weighing bags also prevents passengers from bypassing "heavy bag" fees by moving heavy items from their checked suitcases into their carry-ons, ensuring the airline captures all applicable fees for the weight they are transporting.