Hello,
I need a loan of 0.5 btc that I can repay in 2 months with whatever interest is asked.
What I can offer as collateral is a wallet that has 2.1 btc in it.
I could extract the amount needed from it, but the wallet has a ton of small inputs to form that sum, and in order to not get a too large transaction error I need to make a ton of small transactions to get there and it takes a huge amount of time.
I need the amount faster than that for a urgent matter.
I'm not 100% sure if this is acceptable to anyone here.
I hope it is.
I would hope that you're not serious with such request. But yes why not trust a brand new account?
Just because if you offer a "wallet " as a collateral (I guess you mean a private key that can unlock funds for 2.1 btc)... basically you can keep a copy?

(well, basically this is not a valid collateral).
Moreover why you don't send by yourself all these "small inputs" in one transaction and unlock this amount?
Add a decent size fee and you have your amount in 10-30 minutes.
obviously you don't have a transaction error

that's a really lame/silly excuse.