Это цитата из черновой редакции ВК. По HoME том 6 глава 2. Бинго - примерно то же, что и Фродо...
" 'Well anyway,' said Bingo. 'if Gollum could not be killed, I wish
you had not let Bilbo keep the Ring. Why did he? Why did you let
him? Did you tell him all this?'
'Yes, I let him,' said Gandalf. 'But at first of course I did not
even imagine that it was [one] of the nineteen Rings of Power: I
thought he had got nothing more dangerous than one of the lesser
magic rings that were once more common - and were used (as
their maker intended) chiefly by minor rogues and villains, for
mean wickednesses. I was not frightened of Bilbo being affected
by their power."
Здесь Г. прямо говорит, что считал Кольцо - одно из "меньших", что не особенно опасно. Особой редкостью эти кольца, видимо, не отличались и число их неизвестно.
По поводу оговорки. Не проблема, на мой взгляд. Это разные категории колец - Великие и Ельфийские. Оба (обе... обои...

), короче, и то и то пишется с большой буквы.