Available on the God of War 3 Ultimate Edition and through PSN are an additional 7 challenges. Switch Blade requires you to defeat all enemies within 120 seconds with your weapons switching every 30 seconds.
For a more comprehensive guide to these challenges see grandmort's faq on gamefaqs - www.gamefaqs.com/console/ps3/f...
By far the hardest challenge IMO, requiring a good amount of skill and luck. The first wave are Legionnaires, second come Cerebus hounds, 5 minotaurs appear at the first weapon change and Legionnaire Guardians at the last stage. Your weapons in the order of switching are Blades of Exile, Nemesis Whip, Claws of Hades and Cestus Gauntlets.
In the first phase I found weakening the enemies using the Spirit of Hercules to be a good way of eliminating the Legionnaires. The main issue in this phase is the attacks by the Legionnaires can sometimes interrupt your combos losing you precious seconds. Avoid or block these attacks if you can, if you can kill 12 or 13 before the weapon switch you're in good form.
After 30 seconds you'll switch to the Nemesis whip and the minotaurs will appear, I tried to draw the Legionnaires to where the minontaurs spawn, so you can get some free hits whilst they're coming out of the ground. By this point the arena's getting pretty busy, and using L1 + Square is a good way to get some hits on the minotaurs and give yourself a bit of a breather . Note you don't need to mash the square button, holding it will suffice to keep your attacks going in the air. Hopefully you'll have eliminated a number of cerebus hounds as their grab attack is quite time consuming (unless a number of hounds have piled on you, then the QTE to free yourself is quite helpful to stun the surrounding enemies).
Inflict as much damage as you can on those minotaurs with the whip as they're likely to be your biggest issue to completing the challenge. Once you switch to the Claws it's much harder IMO to damage them, as they have a tendency to block a lot of your attacks and your attacks are also a lot slower.
Use L1 + triangle if you're surrounded by hounds to avoid getting piled on. Best way to damage the minotaurs now are hit and run attacks. Parrying the minotaur's overhead swings (note these overhead swings can't seemed be blocked only parried) is very effective as well. By now the Legionnaire Guardians have started to spawn, you can't do anything to them with the claws so avoid/ignore them.
When you switch to the Cestus things are looking up again. Use your heavy attacks as much as possible to inflict maximum damage in what little time you have. From here on in it's a case of pounding all the enemies with your heavy attacks, hopefully you'll weakened the minotaurs so they won't need too much time to defeat them leaving you just the Legionnaire Guardians to take of.