Easy to learn weapons, difficult to master weapons, and weapon expertise?

[Greywander]

You know how some weapons were considered really useful, not because they were necessarily more effective, but because they required a lot less training to be effective? I'm talking things like spears and crossbows, probably clubs too, maybe a few others. (I'm still baffled that club proficiency isn't universal, yet sling proficiency is.)

I was thinking that some weapons could have an "easy to learn" trait that allows you to add half your proficiency bonus to attack rolls when you're not proficient. For PCs, this likely wouldn't make much of a difference. Every class gets proficiency with daggers, quarterstaves, slings, darts, and light crossbows, which I think covers almost every weapon niche aside from reach weapons. You might see some edge cases like using a hand crossbow with Crossbow Expert without proficiency, but most of the time it's going to be better to use a weapon you're proficient with. Where I'd expect this to make more of a difference is with NPCs. For example, if you needed to arm up a town in order to defend it against an attack. Or maybe you have a follower who isn't trained with combat, but you give them a crossbow so they can at least participate anyway.

This also got me thinking about a corollary trait, where a weapon is "hard to master", but I'm not sure what such a trait might entail. I suppose it could make it more difficult to get proficient with that weapon, but usually anything that grants proficiency with a weapon of your choice treats all weapons as equal (and in any case I don't think this would be a good balancing mechanic). And besides, this distinction already kind of exists in the distinction between simple and martial weapons. My other thought is that it somehow relate to getting expertise with a weapon.

Which then leads to a whole new discussion of what weapon expertise might look like. I think you could have situations where you're making ability checks with a weapon, treating it like a tool, and if you're proficient with that weapon then you'd add your proficiency bonus. But weapon expertise that only applies to ability checks and not to attack rolls seems kind of lame and borderline pointless. At the same time, doubling your proficiency bonus for attack rolls is not a weak effect. At least it wouldn't raise your damage ceiling, just push your average damage closer to that ceiling. That is, until you figure in things like GWM/SS, where double proficiency would completely negate the accuracy penalty after 13th level.

With regards to weapons that are "hard to master", even if we do have weapon expertise, that isn't really a different situation from proficiency. "Hard to master" implies that there's some kind of bonus you could get for "mastering" a weapon, and that the hard to master weapons would require a greater investment. Alternatively, perhaps something that's normally taken for granted is capped by your level or proficiency bonus, limiting your effectiveness until you reach higher levels. "Hard to master" weapons could also just be weapons that have their own feats, representing the extra effort required to attain mastery, but also the additional benefits if you do.

I dunno, maybe this is kind of pointless? But at least the "easy to learn" thing seems like a fun detail to include that might be situationally useful sometimes.

[JNAProductions]

NPCs have the proficiencies the DM says they do.
That said, your "Easy-to-learn" mechanic seems fine to me! Helpful for when PCs don't have their normal gear, at least.

Hard-to-master could be represented by Exotic Weapons-no class grants proficiency in them by default at level one, requiring the Weapon Master Feat or a class feature or subclass feature or something to get. These weapons would only get your normal attack bonus, but could have higher damage dice, better properties, etc. etc.

Like a one-handed 1d12 Exotic Weapon.
Or a 2d8 (maybe even 2d10) two-handed Exotic Weapon.

I dunno.

[Corran]

You could make weapon proficiency something that can be learnt during downtime. So, very very roughly, and using your idea about half proficiency, teaching commoners to fight with weapons of type A would take 1-10 (1d10) days and the DC could be ten. Failing by X or more means they dont improve, failing by less than X means they get to add half proficiency, succeding means they become proficient, and if you so like, succeeding by Y or more means they get some kind of expertise allowing them to add double their prof bonus or giving them some different additional benefit. While doing the same with weapons of type B (which are harder to master), would take more time, would have a higher DC, and the scaling might be less rewarding too (probably go with an all or nothing approach to showcase in an additional way that training in the more difficult weapons is indeed harder and takes more time).

For pc's this probably requires some kind of overhaul when it comes to weapon proficiencies. A combination of class and background could give you a certain number of weapon points which you would then be able to spend on getting weapon proficiencies. With the weapons that are more difficult to master requiring more points. Though you would certainly have to give more incentive on investing on multiple different damage types (such as by giving monsters a combination of resistance and vulnerability to slashing, piercing and bludgeoning) otherwise it wont make much sense going into this whole process. Though as a side effect monster knowledge (rangers?) is useful more commonly.

[Rad]

This is the idea behind the distinction between martial and simple weapons.

That said, I find it puzzling that the weapon system is so poor of variety. "Actions done with weapons" could have a variety close to that of spells, but unfortunately it's usually just a negligible average damage difference.