Those notched rod butts fit in the steel rodholders that are part of fixed fighting chairs on big sport fishing boats that regularly go after marlin, sails, tuna, and swordfish. They are also on some fighting harnesses.
They are of no use to you, and may even cause you some problems when you try to find a comfortable way to hold them, because the metal butt is somewhat sharp and will dig into your stomach or leg. See if you can return it for a "regular" rod with a flat base in the same style. None of the "normal" rodholders that you would be using on a yak will have these pins in them, as you have already noticed.
They are called "gimbal" because the rodholder can move up and down around a pin while fixed in the fighting chair.