When I move my transaction back to the online machine, Armory can check if all the outputs are unspent, if I did something wrong then we are back to square one.
No, it won't work that way. To create a transaction you need to know which outputs to use and the offline machine doesn't know about any outputs at all.
E.g. let's say you have a new address and today (Dec 1, 2013) you received 1 BTC to this address. In order to spend this 1 BTC you will need to refer to the 32-byte hash of that Dec 1, 2013 transaction. Knowing only the address is not enough.