Bodkin Arrows were invented by Mr. Bodkin. He lived during the Middle Ages and was a woodworker. Sometimes he went through the woods and laughed about the bears there.
Those bears had simple bows and used sticks as arrows. Those arrows obviously didn't really work against the bees. Too well equipped those bees didn't care about the sticks hitting their beehive. Peeing down, the bees could watch the dumb bears and make jokes about them.
One day the bears noticed Mr. Bodkin behind a bush who was heavily laughing. He laughed for hours and finally went blue and brown. The bears never ate meat so they thought about a solution to get rid of that blue-brown thingie on the ground. Finally the Elder of the bears found a solution and poked the corpse with one of the arrow sticks.
With a lot of strength the stick got stuck in the rotting meat and broken bones. The strongest of the bear warriors picked the arrow up and drew the bow. It took a while until he found out how to use the stick with the corpse at the end. He drew the bow for hours and finally loosed it, taking aim at the beehive.
The bees looked at it, shocked. They already knew about Mr. Bodkin. Important to know is that Mr. Bodkin was full of scars, with lots of pointy ends - those could damage the beehive heavily and end the Kingdom of bees. The bee queen asked for her queensguard and sent out her best riders to charge down and attack the bears.
The battle took for hours but suddenly the loosened arrow with the bodkinhead ended up in the beehive, destroying the home of the bees. The explosion and penetration was that high and heavy, that the woods burned. Life in the woods ended, but at the end of the day, the Bodkin arrows were invented.
Bodkin arrows do cause more damage to heavy armor, less to light gear. So if you face someone in plate, better use bodkin arrows. For any other kind of armor, tatar and barbed arrows are the better choice.