toucanbuzz
No rule is inviolate
Here's a 3rd edition version:
This exotic weapon resembles a composite longbow but is designed to be used with stirrups, with the archer holding the bow in her feet and drawing it with one or both hands. like a composite longbow. [The Raptoran race would use these while flying, so it was described as being used in flight.] All footbows are made with a particular strength rating, and if your STR bonus is less, you attack with -2 [Disadvantage]. A default bow requires a 10 STR or higher. Each point of STR bonus granted by the bow adds 100g to its cost. A footbow may be fired with both hands pulling back on the bow, increasing the STR bonus to 1.5x.
A footbow is used while seated on the ground, but the archer must be prone to do so and takes a -4 penalty [disadvantage] on the attack roll. [Bows normally cannot be fired from a prone position.][If you've watched video of someone trying fire one of these, I don't know how the heck you aim them at anything, much less your ass is up in the air during your attack.]
Cost: 150gp base
Damage: 1d8 pierce + STR bonus*
Range: 110 / ? [and there's consideration that this bow requires a severe amount of arc. You can't really shoot it at anything in front of you. As such, it was an aerial weapon for D&D purposes, even though it historically did exist to shoot arrows really really far.]
Weight: 3lb
* The maximum STR bonus allowed is based on the STR requirement of the footbow. For example, a 14 STR footbow would cost 350gp and do up to 1d8+2 damage.
[You could consider upping the damage dice to 1d10, but a Footbow is a fairly impractical D&D weapon. It appears the primary advantage was to increase arced range, or for the aerial races, to fire using their feet. You might create a mechanic where if arms and legs are both used, the damage dice have advantage (take the best of two base die rolls).]
This exotic weapon resembles a composite longbow but is designed to be used with stirrups, with the archer holding the bow in her feet and drawing it with one or both hands. like a composite longbow. [The Raptoran race would use these while flying, so it was described as being used in flight.] All footbows are made with a particular strength rating, and if your STR bonus is less, you attack with -2 [Disadvantage]. A default bow requires a 10 STR or higher. Each point of STR bonus granted by the bow adds 100g to its cost. A footbow may be fired with both hands pulling back on the bow, increasing the STR bonus to 1.5x.
A footbow is used while seated on the ground, but the archer must be prone to do so and takes a -4 penalty [disadvantage] on the attack roll. [Bows normally cannot be fired from a prone position.][If you've watched video of someone trying fire one of these, I don't know how the heck you aim them at anything, much less your ass is up in the air during your attack.]
Cost: 150gp base
Damage: 1d8 pierce + STR bonus*
Range: 110 / ? [and there's consideration that this bow requires a severe amount of arc. You can't really shoot it at anything in front of you. As such, it was an aerial weapon for D&D purposes, even though it historically did exist to shoot arrows really really far.]
Weight: 3lb
* The maximum STR bonus allowed is based on the STR requirement of the footbow. For example, a 14 STR footbow would cost 350gp and do up to 1d8+2 damage.
[You could consider upping the damage dice to 1d10, but a Footbow is a fairly impractical D&D weapon. It appears the primary advantage was to increase arced range, or for the aerial races, to fire using their feet. You might create a mechanic where if arms and legs are both used, the damage dice have advantage (take the best of two base die rolls).]