While doing research for the mass combat rules I may or may not end up successfully creating, I kept running into something that has always bugged me about the 5e weapons: the spear.
To start, we have a javelin, a spear, and a pike in the rules to represent the three real-world categories of spear-like weapons. So far, so good.
The spear is a cheap simple weapon, as it should be. The problem is that, more than most other simple weapons, it is a weapon that is also used as a primary weapon by more skilled warriors and trained armies. Mechanically, it isn't on par with martial weapons, and it's a bad choice you probably aren't going to take for a PC. And when I look at the guard NPC statblock with its pitiful spear, I just feel bad.
In addition, there are conceptual issues because an essential part of the historical spear was its reach. Based on my cursory research, real spears were of similar length to glaives and halberds, which do have reach in 5e. But the spear doesn't, for some weird reason. While this is just an annoyance at the normal D&D scale, when you start messing with mass combat considerations, spears don't work. They need to both be usable in one-hand and have reach so they can be used for the actual spear and shield tactics that people used spears for.
But I found something interesting in my research. Apparently there are supposed to be two types of (sub-pike) spears. Thrusting and throwing. Javelins are for throwing, and thrusting spears aren't.
. . .
That was the revelation. What's holding back the spear is that it's being given the Thrown property unnecessarily. Sure, if you throw it it might fly better than if you throw a flail or scimitar, but so would a shortsword and that doesn't have the Thrown property. The thing is that you don't throw your thrusting spear except in extreme situations, because then you don't have it anymore. If you want to throw spears, that's what javelins are for. Carry 7 of them like the Romans.
So here is the spear houserule: Remove the Thrown property; add the Reach property. Everything else stays the same.
Conceptually this puts spears in their correct place on the javelin-spear-pike continuum.
Javelins can be used in melee, but are designed for throwing. (1d6 damage, ranged or melee)
Spears are designed for thrusting, have reach, and can be used either one-handed with a shield or two-handed. (1d6 damage melee reach with shield, or 1d8 damage melee reach two-handed)
Pikes are too big for one-handed use (and obviously have reach). (1d10 damage melee reach two-handed)
Mechanically, they now have a meaningful niche and are still balanced properly with other weapons. PCs and NPCs alike have a reason to choose a spear either at the personal or mass combat scale. This does put them on par with martial weapons, but I'm probably okay with that. Spears have been one of the most popular weapons in history, and this rule makes that hold up.
I'm hoping it works out the way I like. If everyone gives up on longswords and battleaxes and converts to spears, then I've screwed up. Otherwise, I think this should fix it.