You got killed by an Ash Hopper, Wow that is funny.
Well, I have a 17 or a 19, And they can use the Smithing Table to make Bonemold,Chitin, No Nordic Carved, Maybe that's for 20 or a Smithing Perk
Ash Hoppers are pretty nasty if you aren't careful.
Not as bad as those new spiders though. Easy to kill, but if they swarm you, they do TONS of damage.
@OP: I've seen them appearing on higher level enemies around the late 20's mark. If you have the Advanced Armours Perk, you can make Nordic Carved. Not sure about Chitin as far as smithing goes.