PnK Macuahuitl
As of: mc1.12.2-4.0b7 (Oct-2018)
The Macuahuitl is an smart hacking weapon like the Pinkly Hack Sword, with the additional benefit that its smarts get smarter, and deadlier, as you use it to dispatch a variety of mobs over time and across game dimensions. While the hack sword uses cudgel shards for its deadly hits, a Macuahuitl is made with Flaked Obsidian embedded in Beanstalk wood and of course an Entwined Handle.
The Macuahuitl has a simple builtin advancement system that corresponds to a player's proficiency with the weapon. There are four levels or tiers: Novice, Ocelot, Jaguar, and Noble. It is quite a challenge to get to the final Noble level, but as you advance through each tier, you will be richly rewarded. Note that your progress is tied to a particular macuahuitl, so one of the problems you need to resolve it how to keep the damage to your macuahuitl to a minimum.
Expanded tooltip for a used Macuahuitl.
You can repair your macuahuitl with Flaked Obsidian on a standard anvil.
Like the pinkly Hack Sword, you can only enchant your macuahuitl with X-Enchantments. Unlike a pinkly hack sword which only accepts a tiny subset of enchantments, any X-enchantment that works for a standard sword, will remain on your macuahuitl including Unbreaking and Mending.