I found it curious too, that a word for more was a noun... In some "noun-like" cases, I'd rater analyse the situation as an adverb or an adjective, from which the modified word has been dropped (eg. "the more the merrier" seems just a truncated version of "the more people, the merrier party" - the same way as you might say "the faster the better"). Even if that does not hold, I'd still be inclined on treating more as a pronoun, nothing/no-one and everything/everyone, even some are pronouns, so why not more?
Well, this isn't the first time my layman look on the words has lead me astray (the difference between pronouns and nouns seems exeptionally flimsy). The dictionaries I checked mark (the relevant meanings of) more as a noun in english, and the word form for alikh (derivation from adjectival more, ale) is very noun-like in Dothraki.