Why don't you try taking on 25 soldiers at once, lasting 10 minutes in open combat, or killing 100 opponents without dieing? It's not as easy as it may sound. Today I unlocked a lot of achievements from Assassin's Creed and it was great! Unfortunatly, I was unlocking the Eagle's Will (kill 100 opponents without dieing) achievement and wasn't smart enough to remember that I had already unlocked it. So, 1 hour and 300 dead soldiers later, I realized I had unlocked it... Epic phail...