Loading trait on weapons without ammunition

Question

The loading trait reads,

Loading. Because of the time required to load this weapon, you can fire only one piece of ammunition from it when you use an action, bonus action, or reaction to fire it, regardless of the number of attacks you can normally make.

I interpreted this as meaning the weapon can make only one attack per round.

For brevity, can I use this on any homebrew weapon I want to restrict to one attack per round, or is its description fluff too tied up with the ammunition trait for this to be clear? Would it be better to just use the special trait as a general catch-all for anything not pre-scripted by the developers?

The homebrew weapon in question is an oversized spiked flail+maul with 2 striking heads. It deals 2d12 piercing damage, weighs 30 lb., and has the heavy, two handed, and reach properties. I want to simulate the idea of each attack being a big, slow swing which tactically inconveniences the character using it. It's going to be in the hands of a LBEG and used against the players, but I want it to be something they can take from him and use if they'd like after he's defeated. (It's an inconvenient weapon, but at 2d12 it could make for a quick shortcut through first tier random encounters, and possibly be worth a bit of loot once the characters have outgrown it. I award XP by plot progression, so reducing the difficulty of diversionary combat isn't an issue.)

Answer 1

The trait states that you can only fire one piece of ammunition, not that you can only make one attack. For example, someone could use one attack to fire the weapon, and a second one to use it as an improvised weapon to bludgeon an enemy.

Given that you're already homebrewing this weapon with special properties, it's not a stretch to homebrew your own trait for it. Why not add something like:

Unwieldy. Because of the awkwardness of this weapon, you can only make one attack with this weapon per round, regardless of the number of attacks you can normally make.

Answer 2

For clarification, 5e doesn't use fluff text. If the rules say something, then what is said applies. A perfect example of this is the spell text of burning hands, which states that you touch your two thumbs together with your hands flat and fingers pointed outward. That is how burning hands works, not just a "fluffy" description of how it works.

The same reasoning can be applied to the loading property.

Because of the time required to load this weapon, you can fire only one piece of ammunition from it when you use an action, bonus action, or reaction to fire it, regardless of the number of attacks you can normally make.

Since the loading property applies only to ranged weapons, and it implies the weapon must be loaded with ammunition, it doesn't make sense to use it for your homebrewed weapon.

However, since you're already venturing into homebrew territory, what is stopping you from coming up with a new weapon property? Based on your description, you could do something like this:

Slow. Because of the weight of this weapon, you can only make one attack when you use an action, bonus action, or reaction to swing it, regardless of the number of attacks you can normally make.