I am in the Warmaiden's store in Whiterun and see for sale arrows with a damage value of 24! I usually see 8 or 10 damage for sale.

The arrows are "Armour Piercing Broadhead" and he has 100 for sale. He also has Heavy Steel Broadhead at damage 16.

I looked on the Internet and no mention of these arrows (or in the book I have).

Are they added by one of my mods? I only have a few mods:

Skyrim Scaling Stopper
Ranger huts
Fast horse
Realistic blood
Sabre backpack
A food mod
A frostbite mod

Might have missed a mod...

I am level 8.

Any thoughts?

Thanks in advance.

Well those arrows are not in the original game so I would guess it's one of your mods. Most mods have a readme file with discriptions of all the added content. You can also go back and check where you got the mods for descriptions.