Cool, cool prestige class. Very interesting. Looks fairly balanced. I only have a few quibbles/questions.

Quote Originally Posted by The Demented One View Post
Crimson Slash (Ex)
At 1st level, you gain the ability to maim foes with your blade. Once per day, you may declare one melee attack a crimson slash. You must do so before you make the attack roll; if the attack misses, you still lose that use. A creature hit by a crimson slash takes 1d4 points of Str damage. At each odd level, you gain an additional daily use of the crimson slash ability. At 5th level, the ability damage dealt by the crimson slash ability increases to 1d6. At 9th level, you may deal Con damage, rather than Str damage with the crimson slash ability.
What happens on a crit? Do you double the Strength damage?

Quote Originally Posted by The Demented One View Post
Sudden Death (Ex)
At 10th level, you gain the ability to slay a foe before they even realize you’ve struck them. Once per day, you may declare one melee attack a sudden death attack. You must do so before you make the attack roll; if the attack misses, you still lose that use. If the attack is successful, then the enemy you struck is automatically dazed for 1d4 rounds. At the end of those 1d4 rounds, its hit points fall to -10, and it dies. Even creatures immune to dazing are subject to the latter part of this ability.
Is there no save at all? I think a death attack for free, no save is a little cruel - all you've got to do is hit, and you can just KILL a dragon, once a day? Or a Balor? With minimum 7th level to enter the class, you'll be at 17th when you finish the prestige class. I just don't see a 17th-level character having a 50% chance to kill a Balor every day (Assuming the following to hit: +4 from Str, +17 BAB, +4 Weapon for +25; Balor's AC is 35). Or an 80% chance to kill a Marilith, assuming the same to hit as above - CR 17, AC 29. You don't even have to roll to hit a Formian Queen, AC 23. It just dies, assuming you don't roll a natural 1.

For comparison, the monk's Quivering Palm attack requires you to hit and it gives a save.

Just a thought.