Security is a big issue with most people. But I have to be honest, it's not with me. I think it makes me the biggest hypocrite in the world since I am a Certified Information System Security Professional (CISSP). I think that many westerners aren't security conscious, they are paranoid. Don't get me wrong I am sure that it may come to bite me, but there are many reasons why I don't worry about it.
I trust my virtual assistants
None of my virtual assistants have done anything that would make me question their integrity. On the contrary, the fact that when they "do something wrong" they immediately tell me that they'll work on the weekend to fix it tells me that they want to help me and not hurt me (I never let them work weekends).
This is in part to who they are, but also because the Filipino culture is very trustworthy. I am sure there are some bad people in their country. If fact, one of my VAs told me of someone who he worked with who destroyed an entire business because they didn't get paid for a month's worth of work. Even so, that person is not one of my VAs.
See what happens when someone from the Philippines uses your card
Very rarely will a credit card company allow someone from another country use your card without prior authorization. My VAs haven't bought anything for me with my credit card, but I bet that down the road I'll have to get them their own.
Even if they were successful in credit fraud, it's unlikely that you'd have to pay anymore than if your cousin stole your card and went on a shopping spree. You didn't authorize the transaction.
Of course I am not a business lawyer, but I don't worry about my VAs knowing my financial data.
Create and give them only access to what they need
One thing that I do agree with though, is that you shouldn't give them absolutely everything. Be smart about it and give them only access to the stuff they need to get their work accomplished. The more that you give, the more vulnerable you become if something were indeed going to happen.
One way to do this is to use Google apps spreadsheets or Keepass.