It seems like the very easiest, most straightforward way of helping the Ukrainian state in its resistance, as well as the people in their troubles, is to just buy and hold Ukrainian currency. This moves foreign currency into the Ukrainian economy, which will eventually be exchanged for imports presumably including weapons; and allows them to print more cash without causing inflation (since you are by assumption taking the rubles you bought out of circulation). In effect you're making an interest-free loan to Ukrainians in general, and because it was done in a reasonably free and liquid market it will find its way to the highest-value use, as judged by the people on the front.
Am I missing something?













