oh it seems I didn't explain myself properly.
One online machine. 2 instances of armory installed in separate folders. One can access the internet. The other is blocked at firewall level. Or even better in a virtual machine that has no network access.
Ah, so you only have one machine... In that case, the setup would probably be "safer" than a "normal" desktop wallet... a VM with an encrypted disk and no network devices, nor using a shared clipboard might actually be a reasonably safe setup (albeit, you'll need a procedure to transfer signed/unsigned transaction back and forth with the use of a virual usb or something)