Keyloggers can also steal your wallet.dat and your wallet passwords. Considering most viruses has a wallet.dat stealer in it. If you are storing 1BTC, you shouldn't be using a desktop wallet or online wallet. It should be in your cold storage.
I dont know what you are talking about here,
but if you are referring to my quickwallet software's "wallet.dat" then you are mistaken. That wallet.dat contains absolutely no private key. It's just a collection of bitcoin addresses encrypted to ensure privacy, but it has absolutely nothing to do with actualy "wallet.wallet" files like the Bitcoin Core or Armory uses.
Otherwise who would be stupid enough to keep 1BTC if a wallet.wallet file in his infected online pc that is a major target to all kinds of viruses from faucet sites and malware?
It just doesnt seem logical to me.