Try a Temple of the Dawnbreaker and see how that runs for you. It lets you re-roll a Defense die, which is really good and will pay off long term. I, personally, would NOT remove the Defense Ring. While you can only make one Defense roll per attack, you will probably be making multiple defense rolls per turn, so it will pay off, especially if you run the Dawnbreaker.
Also, Hand of Bim-Shalla! Armor, healing, or melee, at any range. Almost a must have in a build like this.
And yes, the Colossus Belt is the way to go. You really need to mitigate Daze/Stun as much as possible.
Also, I think you are missing a few key enchantments. Mongoose Agility is pretty huge for avoiding guards and Vampirism is a great passive healing card, especially if you remove the Regrowth Belt for the Colossus Belt. You also might want to consider Eagle Claw boots as others have mentioned. You could add Cobra Reflexes to make up for missing out on the Reflex Boot's Defense die.
Lastly, consider Enchanter's Wardstone. Having two (or more) of these out makes removing your enchantments painful for your opponent.