I will begin with the comment that I expected military defeat to lead to many democratic failures, while in times past many people were more afraid of military glory. The record here is a bit slim, but Argos appears to be a rare example of both at once. The city as a whole suffered a military defeat and the democracy was (partially) discredited as a result. At the same time, the elite regiment achieved military glory and saw its status enhanced. My other comment, as before, is that our record is very inadequate, so there is a lot of guesswork here.
Nonetheless, here go my predictions:
Extreme polarization: This appears to have been the case, although we do not have enough details to to say much more.
Abandonment of procedural norms: Once again, our information here is insufficient. We do not know what form ordinary democratic politics took in Argos before the democracy was overthrown. But the final overthrow appears to have taken the form of a coup thinly disguised with legal procedures, i.e., the 1,000 killing the democratic leaders and then "persuading" the assembly to vote them into power.
Hm. I seem to be treating polarization and abandonment of procedural norms as sort of axiomatic, things that happen by definition. I originally meant for them to be happening specifically in the context of democratic politics as usual. That may have been the case in Argos, but we just don't know enough to say.
Political violence or private paramilitaries: Political violence, yes. Private paramilitaries, no. The failure of democracy in Argos appears to have taken the form of a coup by the official state military. And so far as I can tell, this was something new in Greece. Up until then, democracies had been overthrown by oligarchies and both had been overthrown by dictators. But up till then, people seeking to overthrow the established government had relied on private paramilitaries, or foreign mercenaries, or treasonable collusion with a foreign army. Armies consisted of citizen-soldiers, each supplying his own gear. So long as the army is co-extensive with the citizenry, it can be counted upon to be loyal. But in Argos the regular army was supplemented with an elite force that saw itself as the real military power, separate from the citizen body and (presumably) sought to shrink the citizen body down to the size of this elite force. That raises some interesting questions about a state like Athens that extends citizenship to men too poor to afford gear and serve in the army. Will the army decide to shrink to citizen body down to itself? Granted, in Athens poor men provided by backbone of the country's military power by serving in the navy. But if the army wants to stage a coup, how can the navy resist? These questions will become very important soon.
The danger on the right. Well, if I define oligarchy as inherently right wing, then yes, the overthrow was from the right. The left wing menace is from dictators holding themselves out as champions of the common people against the oligarchy.
RIGHT WING TRAITS:
Driven more by fear than ambition: No. As with Plataea, Corcyra, and Megara, this does not hold in Ancient Greece. There is nothing to suggest that the Argive oligarchy was driven by fear. It seems, instead, to have been driven by ambition in the belief that this elite military force were the city's true and rightful rulers.
Inability to tell radicals from moderates, fear of middle class being squeezed out: These are sub-categories of fear and do not apply here -- just as they did not apply in Plataea, Corcyra, or Megara.
Not dependent on a charismatic leader: Here I would have to say we don't know. We have at least the name of the leader of the 1,000 -- Byras. We can confidently say he was not a charismatic leader in the sense of appealing to the masses. But we have no idea how charismatic or influential he was within the 1,000. It does appear, though, that this was a military oligarchy rather than a military dictatorship.
Triggered by military defeat: Or, as discussed above, military defeat of the democracy, but military glory for an elite force. It is interesting that this elite force would proceed to make common cause with Sparta, who they had just been fighting. But we can well imagine an ideological affinity between them. Many other countries purported to admire Sparta, but never went to far as to actually attempt to copy them. The Argive elite forces just might have, given the chance.
TYPE OF FAILURE:
Foreign invasion: Argive democracy was not directly displaced by a foreign invading army, but the oligarchy came to power in collusion with a foreign army. As with Plataea, Corcyra, and Megara, the faction that sought the support of a foreign army ended up losing. In some ways this should not be surprising. The side that is winning does not, after all, have any need to seek the intervention of a foreign power. But it is interesting that in none of these cases was foreign intervention able to tip the domestic balance of power in favor of the weaker party. (In Plataea it was strong enough to destroy the city altogether, but not enough to make the oligarchs prevail).
Military coup: See above.
FASCISM: Almost none of the fascistic traits apply.
Middle class populist movement against those above and below: No. I don't think middle class populism or right wing populism was ever invented in Ancient Greece. The overthrow of Argive democracy was purely the action of an elite (military) against the general citizen body.
Driven by fear and ambition, but predominantly by fear: As with Plataea, Corcyra, and Megara, the oligarchs appear to have been driven entirely by ambition.
Paramilitary party claiming a political monopoly: We don't really know whether the 1,000 competed in Argive politics but played unfair. Apparently they sought to legitimize their rule by intimidating the assembly into approving it. But basically this was not a paramilitary party, but a coup by the official military.
I will make short work of the most generally accepted traits of fascism. None of the fear-based or populist traits of fascism apply. The oligarchs were not imperialist at all, but sought a submissive policy toward Sparta. In fact, imperialism in ancient Greece appears to have been mostly a trait of democracy. They probably did not have a charismatic leader, and certainly not the sort of leader-worship typical of fascism. They were anti-liberal in the sense of seeking to narrow and exclude. They practiced political violence. And the oligarchs believed in the right of their group to dominate, though in a very different way from the nationalism of fascism. But basically, they were a military coup by an elite military regiment, which is something different altogether.