I underestimated the full power of all the new buffs that got applied on the Versatile Weapon that got transmitted to the single swing I did. Who wouldn't be shocked if the much bigger enemy and a giant than you would immediately die by a weapon the size of a needle? Isn't that just kind of embarrassing to the giant? Then again, there are many giants that got killed by small beings so why would I be too surprised...
Still, for a single head of the Sea Worm to disappear in just one swing, was very unexpected for me since I expected it to only get damaged and would attack me before I strike for the kill, I didn't mean for it to be a one-hit kill.