ive dabbled in leather....but i am by no means an expert.
my understanding is wax boiling will slightly harden the leather to help it hold shape, but not really to the point of providing protection for 'armor' applications.....so its mostly used for pouches, bags, cups, ect.
boil hardening will provide a lot harder leather, which is what youd look for in armor......but it also makes the leather more brittle and prone to cracking.......this process also causes the leather to shrink considerably.