If Gendry could absorb age, it would have a significant impact on his own aging process as well as those around him. He could potentially live longer and have a youthful appearance even as he grows older. However, if he uses his power on humans, it would have a negative effect on them, causing them to age rapidly and potentially die much earlier than they would otherwise. This could lead to ethical concerns and potentially dangerous consequences if Gendry were to use his power without restraint. Additionally, he may become a target for those who seek the fountain of youth or wish to prolong their lives at any cost.