So Ive been playing Asssassins Creed Brotherhood since yesterday and Im trying to beat this game quickly.  I was wondering if you could unlock armour the traditional way without finding any items.  I really dont want to go out and find thieves just so I could loot their items.  
 
Oh, any tips on raising the assassins?  
Half of my assassins just died and the fucking auto save fucked me over...  Levelling up the assassins seems to take forever and I like it when I could call 3 sets of trained assassinos to my aid.  and what are Assassin Guild Challenges?  I really want Altair's sword

Make them do missions, but only when the success rate is 90% or above. If you complete the VR missions you get Raiden armor, but otherwise you need to raid some tombs or churches to get special armor. 
 
I don't remember much else, it seems like forever ago since that game.

It's just that one set that needs items, isn't it? Yeah, don't bother with that. It's not the best you can get anyway.
 
I'm surprised some of your assassins died. None of mine ever did. If you're having trouble, just send them out on missions but make sure it's <%80 or so. 
 
The challenges are 'ambient' things you get from the different factions, they're all "hire 20 warriors" or some-such thing like that. You can check them in the menu, I think through the DNA database overview thingy. Or if I'm wrong about that, in the base of the respective faction, where they're basically up on a chalkboard somewhere.

item tips anybody?

I haven't even got the assassins for hire yet. I must be running around climbing shit too much.