Tolkien, Lord of the Rings (LotR), etc.

It's possible I'm misremembering, but didn't the valar indeed fight during the war of wrath? Or was it just the lesser ainur?

After some researching online, I am going to steal this from reddit:

From the Unfinished Tales:

To the overthrow of Morgoth he sent his herald Eönwë.

And a line that was changed by Christopher Tolkien in the Akallabêth, mentioned in The Peoples of Middle-earth:

In the Great Battle when at last Eönwë herald of Manwë overthrew Morgoth and Thangorodrim was broken, the Edain alone of the kindreds of Men fought for the Valar, whereas many others fought for Morgoth.

Christopher Tolkien then proceeds to explain this changed line from the Akallabêth:

In SA the reference to Eönwë was removed; and similarly later in the paragraph 'refusing alike the summons of [Fionwë >] Eönwë and of Morgoth' was changed to 'refusing alike the summons of the Valar and of Morgoth'. The reason for this lay in the treatment of the last chapter of the Quenta Silmarillion in the published work. The only narrative of the Great Battle at the end of the First Age (V.326 ff.) derived from the time when the Children of the Valar were an important conception, and Fionwë son of Manwë was the leader and commanding authority in the final war against Morgoth and his overthrow; but the abandonment of that conception, and the change in the 'status' of Fionwë/Eönwë to that of Manwë's herald led to doubt whether my father, had he ever returned to a real retelling of the story of the end of the Elder Days (see XI.245-7), would have retained Eönwë in so mighty and elemental a role. His part was in consequence somewhat diminished by omissions and ambiguous wording (as may be seen by comparing the text in Vol.V with that of the published Silmarillion; cf. also the editorial addition made to the Valaquenta, X.203). There is however no evidence for this supposition, and I now believe it to have been a mistaken treatment of the original text, and so also here in the Akallabêth.

As noted above, Christopher Tolkien notes that he made a mistake in removing the reference to Eönwë being the one to personally overthrow Morgoth in the published Silmarillion version of the Akallabêth (referred to as "SA" in the quote above).

Thus it can be safely concluded that Eönwë is the one who personally chained Morgoth at the end of the War of Wrath.

As for my own head cannon? That is difficult to say... I guess I never imagined too much extra here. I suppose some nonses, but I can't get out of my head is that earendil used the silmaril on his ship the blast Ancalagon with lasers...

My understanding has always been that none of the Valar took part in the War of Wrath.

When the Valar challenged Melkor directly in the Battle of the Powers, Middle-earth suffered massive collateral damage. And at that time there was only a small population ol Elves at the remote Cuiviénen, guarded by detachment of Maiar.

During the War of Wrath most parts of Middle-earth were already populated by the Children of Ilúvatar, so the Valar had to limit their attack force to "just" Maiar and the Eldar of Aman.

Morgoth's personal power had diminished when he slowly shared parts of his might with his "creations", like the dragons. The Valar had to be aware of this; Thorondor was able to maim Morgoth's face while retrieving Fingolfin's body and would have relayed the news of this and the duel to Manwë.

So it's pretty safe to say that the Valar considered their army to be more than adequate to overthrow Morgoth: Maiar to take on the Balrogs and other fallen Maiar, elite Elves for the orc hordes and other "normal level" enemies.

But I also think that an important component is also that the Children of Ilúvatar had to "save themselves" from evil, the Maiar were sent just to level the stakes and capture Morgoth at.the end. The Eldar of Aman needed to be a part of this effort, not just as elite reinforcements but to show unity with their Middle-earth brethren and other Children of Ilúvatar. They all had to renounce Morgoth's evil and rally together to finally prevail after immeasurable suffering.

If the "gods" themselves had just showed up and taken care of the baddies, there would have been none of this hard earned absolution. Which also fits pretty nicely with Tolkien's Catholic worldview.

As how Beleriand was destroyed and "fell beneath the wawes", it could be argued that the Maiar were allowed to use their full power while facing the fallen Maiar, resulting in the utter ruin of the lands. And if the ruined Beleriand was considered to be tainted by Morgoth's lingering evil, sinking the entire region to the sea would be a logical thing for the Valar to do.

My feeling about it is that the Valar didn't participate, I think we would have been told if they had. There were probably quite a few Maiar with Eönwë as you say to deal with the balrogs and Morgoth himself, but to my understanding he was already significantly weakened at this stage because of the marring of Arda (even Fingolfin did quite well in one on one combat, so I think a few strong Maiar could have done the job).