In the Skulls and Shackles adventure path there is an item called: Vindictive Harpoon. Its a +1 harpoon and under the monster that is using it says that it does 1d6. A normal medium size harpoon does 1d8.
Here is the stat block for the harpoon under treasures:
Aura moderate transmutation; CL 9th
Slot none; Price 10,305 gp; Weight 16 lbs.
This +1 returning harpoon (Pirates of the Inner Sea 18) is
made from the jagged, scrimshaw-carved tusk of a narwhal
attached to a 50-foot length of woven sinew. Unlike most
thrown weapons, a vindictive harpoon functions as well
underwater as on land, and its wielder takes no penalties on
attack rolls underwater.
Requirements Craft Magic Arms and Armor, freedom of
movement, telekinesis; Cost 5,305 gp.
Now I looked up the stats for a harpoon in the Pirates of the Inner Sea book, pg 18, and it says that a medium sized harpoon weighs 16lbs. So the stat block above has the weight of a medium weapon but the stat block under the NPC says it does small creature damage, 1d6. What gives!? Do magic weapons auto-size like magic armor in Pathfinder? Or am I missing something.
Thank you for any help.