Had a few more thoughts on the White Council scaling, as our current course would see them gain a "At Most
High 3-A" rating, which completely shatters the scaling chain.
But firstly, let me note that the Nazgul, Gandalf the Grey, and the Balrogs should probably scale to
7-A, be it solidly or "likely" or "possibly".
The
Unfinished Tales discusses the meeting between the Nazgul and Saruman of Many Colours, noting first
"
Two days after Gandalf had departed from Orthanc, the Lord of Morgul halted before the Gate of Isengard. Then Saruman, already filled with wrath and fear by the escape of Gandalf, perceived the peril of standing between enemies, a known traitor to both. His dread was great, for his hope of deceiving Sauron, or at the least of receiving his favour in victory, was utterly lost. Now either he himself must gain the Ring or come to ruin and torment." - The dread here is twofold, the dread of failing to deceive or serve Sauron is present, but also the potential dread of coming to ruin and torment with the arrival of the Witch-King and the Nine.
There's some more to note here, as "
The Lord of the Nazgûl spared the life of the Wormtongue, not out of pity, but because he deemed that so great a terror was upon him that he would never dare to speak of their encounter (as proved true), and he saw that the creature was evil and was likely to do great harm yet to Saruman, if he lived. So he left him lying on the ground, and rode away, and did not trouble to go back to Isengard. Sauron's vengeance could wait. " - implying the Nazgul could have done harm to Saruman had they elected to go back to Isengard and attack.
Version C of this text expands on this and notes - "
In C, on the other hand, the Black Riders arrived at the Gate of Isengard while Gandalf was still a prisoner in the tower. In this account, Saruman, in fear and despair, and perceiving the full horror of service to Mordor, resolved suddenly to yield to Gandalf, and to beg for his pardon and help." - potentially implying the combined might of the Nine is something Saruman fears.
Thus, it is suggestible Saruman can be harmed by the Nazgul, which is congruent to Glorfindel being unable to withstand all the Nine (be it circumstantial or otherwise). There is also this
"
Two days after Gandalf had departed from Orthanc, the Lord of Morgul halted before the Gate of Isengard. Then Saruman, already filled with wrath and fear by the escape of Gandalf, perceived the peril of standing between enemies, a known traitor to both. His dread was great, for his hope of deceiving Sauron, or at the least of receiving his favour in victory, was utterly lost. Now either he himself must gain the Ring or come to ruin and torment. But he was wary and cunning still, and he had ordered Isengard against just such an evil chance. The Circle of Isengard was too strong for even the Lord of Morgul and his company to assail without great force of war. Therefore to his challenge and demands he received only the answer of the voice of Saruman, that spoke by some art as though it came from the Gate itself. " - Which implies that, while it would take great effort, the Nazgul could have assailed Isengard and won if they had elected to, as the only company the Witch-King had was his fellow Ringwraiths.
Gandalf the Grey was able to fend off the combined Nine at night, albeit only that night as he had to flee immediately, which allows him to scale too. The Balrogs naturally scale as well. They are thus all comparable, and thus ratable as 7-A from downscaling to Sauron's shaking of Mordor. That key of Sauron should then gain an "At Least" in my opinion, doubly so since he was doing that as a casual message.
Now, to the earlier problem. Glorfindel is comparable to the Maiar in Valinor who were his friends, and Olorin was one of them. However, Glorfindel and Galadriel (who is above him) scale below Gandalf the White who is below himself as Olorin to an unknown degree, and is below Sauron (W/O Ring) whose best feats are only around 7-A, albeit somewhat casually. We can just say screw it, and have everyone under the sun have an "At Most High 3-A" key, but it simply doesn't work with how the displays of might work in LOTR. At least in the Silmarillion, we know the Ainur are capable of cosmic feats, with the Greater Maiar being used against Valar as weapons while being comparable, while the Valar themselves are able to make constellations and control the material universe at will. The Eldar then scale off that.
In LOTR, we lack that solidity, as the Istari are meant to be limiting their power, Sauron is a crippled mess, and all the powerful Eldar who scale directly to the Greater Maiar are gone. All the best feats are relatively limited, and the only tie to the upper scaling comes from Glorfindel being almost a peer to the Maiar of Valinor. But this is a general statement, which may imply he is a peer to Olorin, or only the lesser Maiar who would be far weaker than Olorin (like... Tilion somehow...) Now, I may be arguing from incredulity here to some extent, but it feels incredibly iffy to scale everyone from Aragorn to the Nazgul to the Greater Maiar based on a line about Glorfindel that may or may not refer to the likes of Olorin.
My suggestion is to do the same thing we are doing with Ancalagon, and give him a "likely far higher" note, to acknowledge he may scale to the likes of Olorin, but that it is not certain, due to the general way the statement may be applied, and due to the lack of displayed showings that he can scale to. The same applies to those who scale to him.