In his answer to Q: '...quo plus..., eo plus ... ' translation?, Joonas offered the example:
"quo plus edo, eo laetior sum." = "The more I eat, the happier I am.",
in which,
"quo plus...eo plus" = "the more...the more".
Continuing, Joonas: "'quo' & 'eo' are neuter ablatives, but it may be better to see the pair as a fixed-phrase."
An example offered by Cerberus, in CHAT, recently:
"quo plus eo melius." = "The more the better."
This example is slightly different; the second adverb "plus" replaced by adverb, "melius".
In these, "quo" is the (neuter-ablative) relative pronoun; by/ with/ from/ in, agreeing with an antecedent noun, "whom" or "what"; but, there isn't an antecedent noun in these examples.
Easier to understand is the role of demomstrative pronoun, "eo" = "in this (situation)" (presumably).
What is the role of "quo" in these examples?
What if it was omitted?
"plus...plus" = "more and more" (Oxford);
"plus eo melius" = "the more, in this situation, the better"?
In order to say:
"The more you have, the meaner you become!";
using this construction, is it:
"quo plus habes, eo avare fis/ es!"?