In the game skyrim where can I find the best one handed weapon?

Swords refers to one-handed weapons and it appears that 'Chillrend' is the strongest.

Type: One-Handed

Weight: 15

Damage: 40

Effects: Target takes 25 frost damage. Chance to paralyze the target for 2 seconds

In the secret room under Riftweald Manor in Riften. You can find this weapon while doing the Thieves' Guild quest The Pursuit, inside an Expert level display case.

Check out a list of weapons that you can employ during different types of battle depending on your chosen skills at Primagames.com.