is there a weapon that has an attack rating above 6 in elder of the scrolls oblivion?

Answer 1

It depends on two factors - your skill with that particular type of weapon, and the weapon itself...

I've had some swords as high as 24 - I think this was a Daedric Claymore, or perhaps it WAS Umbra ;);)

(This was with Long Blade at 100 though)

Answer 2

THREE things determine a weapons attack rating. The material, your skill with the weapon type, and the condition of the weapon. If you raise your armorer skill to 75, you can repair items to 125, which increases the rating even higher than its base level.

For example: Blade determines the damage rating of Swords and Daggers (including Claymores). Blunt determines the damage for Maces, Axes, Clubs, and Warhammers. Marksman determines the damage for bows and arrows.

If you skill is high enough, the highest attack rating I've seen is 33 (Umbra with Blade skill of 100 at condition of 125). Daedric weapons (the best non-enchanted weapons available) top out in the high 20's at condition of 125.

Weapon availability is restricted by your level.
Iron 1
Steel 2
Silver 4
Dwarven 6
Elven 9
Glass 12
Ebony 16
Daedric 20

Silver and Daedric weapons also have the advantage of being the only non-enchanted weapons capable of damaging ghosts, wraiths, or Will-o-the-Wisps.

Answer 3

Depending on your level. Umbras Sword is usualy 7 or more.