PEACH time.
Quote Originally Posted by Quiddle View Post
Prerequisites
To qualify to become a Vorpal Warrior, a character must fulfill all the following criteria.
Skills: Kn(the planes) 5 ranks
BaB: +5
Special: Must have killed a creature of an appropriate challenge with a critical hit.
Maybe add weapon focus with any slashing weapon?

Quote Originally Posted by Quiddle View Post
Hit Die: D10
Class Skills: The Vorpal Warrior's class skills are Acrobatics(Dex), Climb (Str), Intimidate (Cha), Knowledge (the planes), Sense Motive (Wis), and Swim (Str).
Skill Points at Each Level: 4 + Int modifier
You need to add profession and craft, and a few other skills (ride, survival) that are on the fighter list wouldn't hurt either.

Quote Originally Posted by Quiddle View Post
Blade of Infinite Edge(Ex): For rounds equal to her base attack bonus per day a Vorpal Warrior can grant any slashing weapon that she wields the vorpal quality. If a weapon that she wields during this effect has the vorpal quality from another source she can decapitate on the next highest number. These rounds can be started or stopped as a free action but must be used in minimum of one round increments.
Alright. Basically the class's bread and butter, even if its mostly situational.

Quote Originally Posted by Quiddle View Post
Force Wave Slash(Su): By imposing a penalty up to -5 on her next attack roll a Vorpal Warrior may increase the range which she can make her next attack by 5ft for every -1 she imposes on herself.
I think what you're trying to say is "A Vorpal Warrior may take a penalty on attack rolls to attack at a range at a rate of -1 to 5 ft of range. The Vorpal Warrior may not take a penalty greater than -5 for this ability." Something like that.

Quote Originally Posted by Quiddle View Post
Cleaver of Fragmentation(Ex): A Vorpal Warrior can score critical hits against targets who are immune to precision damage. While wielding a weapon with the vorpal quality a Vorpal Warrior deal double damage for the purpose of sundering.
This is good. You should maybe add something about killing creatures that can survive without a head, or you end up decapitating monsters and accomplishing nothing.

Quote Originally Posted by Quiddle View Post
Cut the air(Ex): Instead of making a reflex save a Vorpal Warrior can choose to make an attack roll with a slashing weapon and use the result instead. If a Vorpal Warrior makes a reflex save this way she avoids the effect as if she had evasion.(This would manifest as slashing a fireball away or jamming a sword into a wall before falling through a pit.)
Very cool, though you might want to put some sort of limit on it. Maybe have it burn a round of Vorpal?

Quote Originally Posted by Quiddle View Post
Bonus Feat(Ex): Starting at 3rd level and every 3 levels after a Vorpal Warrior gains one bonus Fighter Feat the she qualifies for.
Nice, although you might want to say that you can add 1/2 your Vorpal Warrior levels to your effective fighter level, to let them get to better feats.

Quote Originally Posted by Quiddle View Post
Unstoppable Force(Ex): At 4th level a Vorpal Warrior gains the ability to cut through anything that stands in her way, ignoring all hardness and DR while wielding a slashing weapon.
Except DR/Epic? Might be worth adding that.

Quote Originally Posted by Quiddle View Post
Spacetime Rending Strike(Ex): By slashing through the very fabric of space a Vorpal Warrior can travel directly to her desired destination, skipping the area in between. Starting at 5th level as a standard action while wielding a weapon with the vorpal quality a Vorpal Warrior can instantly transfer herself from her current location to any other spot within a range of 400ft+40ft/bab. This teleportation leaves behind a tear in the fabric of existence until the Vorpal Warrior's next turn that allows others that are on the space where the Vorpal Warrior used this ability to instantly appear in the closest unoccupied space. The space where the Vorpal Warrior used this abillity and the space where she teleported to are counted as being adjacent, having line of sight, and effect. Similarly creatures that are on the space that the Vorpal Warrior used this ability to get to may choose to teleport back to the closest available space to the starting point.

At 7th level a Vorpal Warrior can now use this ability to cut paths to different planes. A Vorpal Warrior can now reach any other plane, though she appears 5 to 500 miles (5d%) from her intended destination unless her destination is one which she has been within 100ft of within the past 5 hours.
Alright, I see what you're doing, it's just complicated. The plane shifting part is good, and so is the pseudo dimension door. I don't know how useful the "leaving a portal open" bit is, but it's not bad.

Quote Originally Posted by Quiddle View Post
Unceasing Blood Fountain: The critical multiplier of and slashing weapon wielded by a Vorpal Warrior is increased by one.
Typo. You put of and. Other than that, strong but not overly so.

Quote Originally Posted by Quiddle View Post
Swordsman of Incredible Luck(Ex): Upon reaching level 8, if a Vorpal Warrior fails to confirm a hit that would cause a decapitation she still scores a critical hit on that attack.
Good. This gives them a bit more oomf, and makes missing vorpals more acceptable. You could consider puting this a little earlier.

Quote Originally Posted by Quiddle View Post
The Heads Will Roll(Ex): At ninth level the range that a Vorpal Warrior decapitates when using a vorpal weapon increases by one.
Does this stack with the ability granted by blade of infinite edge? I would assume so but it's worth asking.

Quote Originally Posted by Quiddle View Post
Snicker Snack(Su): In the hands of a Vorpal Warrior any slashing weapon gains the vorpal quality. If the weapon would gain or already has the the vorpal quality then this ability grants the blade grants the weapon the keen and speed enchantments instead.
It's a pretty good capstone, especially because of all the abilities it lets you use at will. You could probably swap keen and speed for pounce though, as that might be more useful.

Other than that, looks good. Nice work.