subtilize

verb
  1. 1

    To make subtle; to make thin or fine; to make less gross or coarse.

  2. 2

    To refine; to spin into niceties.

    โ€œto subtilize argumentsโ€

  3. 3

    To use subtle arguments or distinctions.

Source: https://en.wiktionary.org/wiki/subtilize