I think you are asking the wrong questions. If you don't arm the Ukrainians now, then there won't be a parliament in 5 years. It's actually this type of questioning that led to the fact the Ukrainians weren't armed before the invasion. They could have already been trained on NATO-standard weapons, and supplied with "offensive" weapons. The Ukrainians were even willing to pay big bucks, but everyone was afraid of Putin. That's what appeasement gets you. War. Just like with Czechoslovakia in 1938.

And I seriously doubt that much of the arms shipments find themselves in the hands of Azov anyways. They have plenty of sponsors and plenty of sources to get their own arms. Plus it's a warzone now, so after hostilities end, there will be plenty of arms around. So anyone will be able to get them. For example, the Ukrainians are picking up plenty of heavy offensive arms from the Russians (either captured or abandoned).

Either way, Ukraine isn't Afghanistan, where the Taliban has now picked up all kinds of nifty toys after the withdrawal of US troops. The Ukrainian army isn't going to collapse and won't be overwhelmed by a small militia group. Plus, the main battle elements of Azov (the original Azov), are situated in Mariupol. Very hard to get arms shipments in there now.

And yes, there certainly will be an upswing of nationalism in Ukraine after the war. That's why they should have been offered an EU and NATO perspective already now. Not membership, just a promise of membership. If this doesn't materialize soon, then the Ukrainians might feel betrayed. Then certainly you could have an upswing of far right sentiments.

Anyways, there is much more danger coming from the far right in places like France or the US, than in Ukraine. Discussing “Nazism” in connection with Ukraine is falling for Putin’s propaganda. The country never had a problem with the far right that was bigger than that of any other European country.