One of my favorite things to do recently is to take cracks specifically at game mechanics I don't have experience with yet, to build up my knowledge base and system mastery for more complicated homebrew projects down the line.
So far, I've learned that weapons in 5e are fairly comprehensive and have very little wiggle room to add new material. Rather than let that be a deterrent, I've found the areas that 5e's weapon spread hasn't covered, and used that to bring back perennial favorite D&D weapons, and to bring in new stuff that fits the genre all the same.
...Problem is, in the first swing at it I had very little idea of what the parameters of these weapons should be. But, you all helped me with that quite a bit! Let's see how:
WHAT I CHANGED:
- Adjusted damage values for Bladed Fan, Spiked Chain, Jian, Katana, Kusari-Gama, Nunchaku, and Sap.
- Removed Dwarven Throwing Hammers and Kukri because unknown to me the PHB's light hammer already covered that niche, and the Kukri wasn't coming together right.
- Added Machete and Tonfa, both providing very interesting dual wield options.
- Reworked properties for the katana, sap, and nunchaku.
- Changed proficiency requirements. You must now trade three Martial proficiencies for one Exotic proficiency, and two Simple proficiencies count as one Martial proficiency for this purpose.
- Tweaked Double Weapon property, mostly for clarity.
- Tweaked Grappling property, to keep players from grappling two people at once with a spiked chain.
- Added note on Exotic Weapons and monk weapons.
- The spiked chain as a two-handed weapon that deals 2d4 damage interacts in an interesting way with the fighting style Great Weapon Fighting. I don't see it as particularly game-breaking, just nice, and a small homage to the spiked chain's history as a powerful, optimal weapon.
WHAT I LEARNED:
- Special properties are probably the way to go with differentiating weapons, but not overly powerful and only where they make sense.
A newer version of this option is available.