[HerenIstarion]

For all their 'sin' the Noldor are the perfect 'shock troops' to hit Morgoth with - & the reason they are so 'perfect' in that role is not because of their remaining virtues, but because of their 'vices'

Working backwards from that statement:

pride and anger = good tool to fight Morgoth

since pride and anger ≠ humility and calmness
and
good tool ≠ bad tool

so humility and calmness = bad tool to fight Morgoth

Yet Morgoth is finally overthrown by the Host of the West, which mainly consists of humble and calm Vanyar. Proud and andry Noldor are crushed. But:

Valar re (The delay I needed to find appropriate piece of textual evidence :

you seem at the same time correct and erring in your judgement. Let him answer who told us the story:

Myths Transformed, HoME X

This appearance of selfish fainéance in the Valar in the mythology as told is (though I have not explained it or commented on it) I think only an 'appearance', and one which we are apt to accept as the truth, since we are all in some degree affected by the shadow and lies of their Enemy, the Calumniator. It has to be remembered that the 'mythology' is repre¬sented as being two stages removed from a true record: it is based first upon Elvish records and lore about the Valar and their own dealings with them; and these have reached us (fragmentarily) only through relics of Númenórean (human) traditions, derived from the Eldar, in the earlier parts, though for later times supplemented by anthropocentric histories and tales. These, it is true, came down through the 'Faithful' and their descendants in Middle-earth, but could not altogether escape the darkening of the picture due to the hostility of the rebellious Númenóreans to the Valar.
Even so, and on the grounds of the stories as received, it is possible to view the matter otherwise. The closing of Valinor against the rebel Noldor (who left it voluntarily and after warning) was in itself just. But, if we dare to attempt to enter the mind of the Elder King, assigning motives and finding faults, there are things to remember before we deliver a judgement. Manwë was the spirit of greatest wisdom and prudence in Arda. He is represented as having had the greatest knowledge of the Music, as a whole, possessed by any one finite mind; and he alone of all persons or minds in that time is represented as having the power of direct recourse to and communication with Eru. He must have grasped with great clarity what even we may perceive dimly: that it was the essential mode of the process of 'history' in Arda that evil should constantly arise, and that out of it new good should constantly come. One especial aspect of this is the strange way in which the evils of the Marrer, or his inheritors, are turned into weapons against evil. If we consider the situation after the escape of Morgoth and the reestablishment of his abode in Middle-earth, we shall see that the heroic Noldor were the best possible weapon with which to keep Morgoth at bay, virtually besieged, and at any rate fully occupied, on the northern fringe of Middle-earth, without provoking him to a frenzy of nihilistic destruction. And in the meanwhile, Men, or the best elements in Mankind, shaking off his shadow, came into contact with a people who had actually seen and experienced the Blessed Realm

In their association with the warring Eldar Men were raised to their fullest achievable stature, and by the two marriages the transference to them, or infusion into Mankind, of the noblest Elf-strain was accomplished, in readiness for the still distant, but inevitably approaching, days when the Elves would 'fade'.
The last intervention with physical force by the Valar, ending in the breaking of Thangorodrim, may then be viewed as not in fact reluctant or even unduly delayed, but timed with precision. The intervention came before the annihilation of the Eldar and the Edain. Morgoth though locally triumphant had neglected most of Middle-earth during the war; and by it he had in fact been weakened: in power and prestige (he had lost and failed to recover one of the Silmarils), and above all in mind. He had become absorbed in 'kingship', and though a tyrant of ogre-size and monstrous power, this was a vast fall even from his former wickedness of hate, and his terrible nihilism. He had fallen to like being a tyrant-king with conquered slaves, and vast obedient armies.

The war was successful, and ruin was limited to the small (if beautiful) region of Beleriand. Morgoth was thus actually made captive in physical form, and in that form taken as a mere criminal to Aman and delivered to Námo Mandos

emphases mine