This is for AD&D 2e S&P.
We love AD&D 2e in the house, and we LOVE the Player's Options books.
In Combat and Tactics they introduced weapon styles and my Blackstone campaign includes several unique styles, including the beloved (by my darling wife Jennifer 'BLOOD! BLOOD AND SKULLS!' Stump) Headsman's Style which can be used with the great axe, bardiche, and greatsword.
To use the Headman's Style you must already have two levels in the Two-Handed Weapons style and be at least specialized in great axe/bardiche/greatsword. The first level in Headsman's Style gives you an additional +1 damage and the second gives you a +3 (total) to damage
Which leads us to the magic item the Headsman's Axe.
This great axe is normally +2 to hit and damage. If you have both levels in the Two-Weapon Style it is +2 to hit and +3 to damage. If you have one level in Headsman's Style it is +3 to hit and +4 to damage. And if you have both levels in Headsman's Style it is +5 to hit and +7 to damage (not including style bonuses!).
Other style-related magical weapons exist, of course