Thank you. I probably don't need to go into classical Japanese, at least now or for a while.The meaning is the same as より. も adds an intensive nuance to it.
よりもの意味 - goo国語辞書
Classical verbs/adjectives conjugate completely differently from the modern ones. For instance, the negative form is 濃からず, not 濃くない, and the past forms are 濃かりき or 濃かりけり, not 濃かった.
Classical Japanese language - Wikipedia
Classical languages still remain often in proverbs, as you quoted, or maxims such like 青は藍より出でて藍より青し or 芝生に入るべからず, but you would never use it in daily conversations.
I can't think of any situations where it's sensitive.