If Gendry had the ability of workers from Age of Empires, he would be able to gather resources much faster and efficiently. He would also be able to construct buildings and repair them quickly, making him a valuable asset in battle. Additionally, he could create units and participate in combat, potentially turning the tide of a battle in a war. However, it is important to note that Gendry is not a trained soldier, so he may not be as effective in combat as experienced warriors.