Old School: Weapon Mastery

If you had the D&D Masters Boxed Set and/or D&D Rules Cyclopedia and wondered about the Rules on Weapon Mastery, you might be surprised that their early form appears in the August 1976 issue of the Dragon as an initial idea that allows your character to progress from a basic proficiency to expert in an assortment of Weapons (including some exotics that dont make the Rules Cyclopedia).
Its fully developed form appearing nine years later in 1985 in the D&D Black Box one year short of the expiry of 'abandoned' intelectual property rights held by the Author of the Article.

Weapons You might Enjoy
Some weapons such as the 'Dwarf Hammer' and the Morning Star don't progress in power, as the wielder increases in weapon proficiency which is a pity.

The Two handed Sword requires a minimum Strength of 16 and Dexterity of 9 just to use, while the Two handed Battle Axe can be used single handed with the same stats (Str 16, Dex 9). Thats right...Your Conan can wield a battleaxe in each hand once he achieves two weapon proficiency, inflicting 1d12 damage with expert skill (skipping right over 1d10 from 1d8).