It is an allegory for concentration of spiritual power in what is left rather than relying on 'perfection'. You cannot see reality the same way once an advanced initiate.
To understand this more, you need to understand Nietzsche's references in Thus Spake Zarathustra to how some people may lose an eye and are mocked, but some people may appear physically perfect but are just one gigantic eye (lacking depth, unable to process information) or whatever other organ (ear, leg, penis, whatever)... and nothing else, are considered 'valid voters', 'the height of culture' and so on by the mediocre.
The DEFORMITY OF THE SOUL is still there in a pristine, young body acclaimed by everyone. Look at our present-day idols that make billions, they are valid in varying extents to what they do, but they are not superhuman of intelligent divinity like Leonardo da Vinci, let alone the Gods. Leonardo in his own time was overlooked in terms of what he could contribute to elevate humanity in favor of idols more acceptable to a younger mind.
Beyond spiritual matters, the regular goy Vikings (who considered a true Viking young, beautiful, capricious and violent) considered deformities and even old age to be abhorrent and a writeoff, that's the natural state of primitive humanity. So it is a partial rebuke of that mentality by their priestly class.
People cannot take this too far, obviously. The point is not to glorify disability, cripple-worship and retardation like Christianity and late stage Rome did. Things like the latter being 'accepted' require an adjustment back to that Viking mentality - like when Rome burned or in 1933.