Versatile is a pretty useless category. It shouldn't decrease weapon damage.WotC almost gave us a weapon system that complied with an item budget. I wish they had just made all weapons comply, and then added a sidebar explicitly saying "If you want to invent a new weapon, go for it. Just use this system."
Die progression: 1d4, 1d6, 1d8, 1d10, 1d12
Base damage for 1H simple weapons: 1d6
Qualities that increase damage one die: Martial, Two-Handed, Heavy
Qualities that decrease damage one die: Finesse, Light, Reach, Versatile (+1 step if used 2H)
(Note: I'm not quite sure how to fit "thrown" into this. It's advantageous, so it should cost something. Maybe distinguish between "can be thrown" and "must be thrown"?)
Note that some weapons don't fit this model. For example:
- Longsword, Warhammer, and Battle Axe would have to have the Heavy tag added, or damage reduced, in order to be Versatile.
- Rapier is 1d6
- Whip is under budget. So you could make it Light, or Simple, or increase it's damage
Also, I haven't fully through through how ranged weapons fit into this. Because ranged attacks...especially bow/crossbow attacks with their increased range...are so powerful in 5e, I would automatically start one die lower. So maybe short bows end up doing 1d4 and long bows do 1d6. I know, heresy. So maybe have to invent some new tags.
I don't think thrown needs to reduce damage. It's fairly limited (weapons with low damage dice, and generally low range). If you want it to reduce damage do it only for weapons that have significant range like the javelin (if the short range is less than you can generally move it shouldn't reduce damage).