Equipment
Martial Ranged
Greatbow d10 req Str 15 200gp.
Ogre Bow d12 req Str 19 450gp
Strength increases damage without getting into a Dex+Str situation.
Perhaps also:
Longbow d8 req STR 12
With all of these weapons being two-handed heavy.
Sounds great, except for...as said before...drawing a bow does not require high overall body strength...which is what the D&D strength score is...and it still bases extra to-hit and damage on the character's strength, and not that of the bow.
All that's required to use such a bow is "specialized strength"; a strength developed in the muscles needed to draw a high-pull bow, and ONLY the muscles needed to draw a high-pull bow. The rest of the body's muscles are superfluous for using a bow.
Just because English Longbowmen used bows with draws as high as 150 to 200 pounds, does not mean they all had at least a 12 Strength or higher, or a crazy high strength like 15 for your Greatbow. Longbowmen, not being primarily melee fighters, likely had strength scores closer to the average strength of men in general: Strength 10 or 11 in D&D terms. They may have been in a little better shape, being part of a militia, but even that might only give a bump of one or two to their average strength. So, with an average strength among English Longbowmen around 10 to 12, just as many English Longbowmen had strengths below those numbers as those who had higher numbers.
That would mean that according to your strength requirements, a significant portion of England's Longbowmen weren't physically strong enough to do what they actually did in battle after battle, and successful strikes by them wouldn't do the amount of damage they were known for.
I guess the history books are wrong...
So, to do this right, require either a Feat or class build/archetype, OR the Strength requirement, and give the bow an independent strength score (not the character's strength score). This way, both characters that spend the years of training (Feat or class build/archetype), and characters that already have a high strength can utilize them, and you get the higher bonus to hit and damage.
Feats (adapted from [MENTION=8313]cperkins[/MENTION] )
MIGHTY ARCHER
Thanks to extensive practice with powerful bows (Mighty property), you gain the following benefits:
• You can utilize bows that you have proficiency with, that have the Mighty property with a STR score of up to 18.
MIGHTY ARCHER EXPERT
Thanks to extensive practice with mighty bows, you gain the following benefits:
• You can utilize bows that you have proficiency with, that have the Mighty property with a STR score of up to 20.
• You gain an extra attack when using the attack action on your turn for a ranged attack with shortbow or longbow that you have proficiency with, in addition to any extra attacks provided by your class.
• Being within 5 feet of a hostile creature doesn’t impose disadvantage on your ranged attack rolls.
• Before you make a ranged attack, you can choose to take a - 5 penalty to the attack roll. If the attack hits, you add +10 to the attack’s damage.
WEAPON PROPERTIES
New Property
Mighty. A shortbow or longbow with this property has it's own STR score. A character must either possess proficiency in bows with this property, or have an equal or higher STR score, to utilize them. You may add the STR bonus of your bow (if higher), instead of your own DEX bonus, to attack and damage rolls when attacking with a mighty bow. You may not add your own STR bonus (if higher than the bow) to attack and damage rolls. The range of any shortbow or longbow with this property is increased to 200/800. Damage dice are increased from 1d6 to 2d4, or 1d8 to 2d6. The price of shortbows or longbows with the Mighty property increase by 25gp for bows with a STR score of 12, with an additional 10gp for every two points of STR above that (+25gp for STR 12, +35gp for STR 14, +45gp for STR 16, +55gp for STR 18, +65gp for STR 20, etc.).
Some quotes about longbow training:
From the Historum History Discussion Forum
http://historum.com/ and this thread in particular
http://historum.com/medieval-byzantine-history/24934-how-did-english-longbowmen-train.html
(The original site this quote is attributed to is no longer accessible.)
For a long time I doubted people drawing 150 lb bows. Then I came across some pictures showing the Medieval method of pulling the bow. The common method of shooting a bow these days is the Victorian method. This is where you pull the bowstring back with the small, Rear Deltoid Muscle to the chin or eye and aim down the arrow-shaft. The main focus is accuracy. To pull a heavy bow you have to learn to shoot with the Medieval method. This method involves leaning forward in pulling the bowstring back with the larger Latissimus Dorsi Muscle while squatting down a bit for balance. As you straighten up your hand will naturally land by your ear-lobe. These are the same muscles you use to do a chin-up. So effectively you are doing a one handed chin-up into the bow.
In the Medieval method, the Latissimus Dorsi Muscles involved start under your arm and go all the way down near your waist. This muscle group is much larger then the pectoralis Muscles (chest). This muscle group is only second in size to the Quadricep Muscles group (legs). The Latissimus Dorsi Muscles also have a mechanical leverage advantage because of the way they are attached to the arm. There is a good deal of space between the joint and where the attach to the bone.
From Wikipedia - English Longbow - attributed to Dr. A.J. Stirland. Raising the Dead: the Skeleton Crew of Henry VIII's Great Ship the Mary Rose. (Chichester 2002).
Skeletons of longbow archers are recognisably adapted, with enlarged left arms and often bone spurs on left wrists, left shoulders and right fingers.
Also from Wikipedia - Acromion/Os acromiale:
In human anatomy, the Acromion (from Greek: akros, "highest", ōmos, "shoulder", plural: acromia) is a bony process on the scapula (shoulder blade). Together with the coracoid process it extends laterally over the shoulder joint. The acromion is a continuation of the scapular spine, and hooks over anteriorly. It articulates with the clavicle (collar bone) to form the acromioclavicular joint.
...
Os_acromiale
The acromion has four ossification centers called (from tip to base) pre-acromion, meso-acromion, meta-acromion, and basi-acromion. In most cases, the first three fuse at 15–18 years, whereas the base part fuses to the scapular spine at 12 years. However, in between 1% and 15% of cases, this osseous union fails and the acromion remains a separate bone. This condition is referred to as os acromiale, but rarely causes pain. Earlier estimates of its prevalence were as low as 1.4%, and this higher estimate was made by Sammarco in the year 2000, based on radiographic and anatomical studies.
This feature was common in skeletons recovered from the Mary Rose shipwreck [which carried a contingent of 300 archers]: it is thought that in those men, much archery practice from childhood on with the mediaeval war bow (which needs a pull three times as strong as the modern standard Olympic bow) pulled at the acromion so much that it prevented bony fusion of the acromion with the scapula.
And Wikipedia again, but attributed to Trevelyan, G. M. (2008). English Social History – A Survey of Six Centuries – Chaucer to Queen Victoria. Longman.:
From a record of how boys and men trained to use the bows with high draw weights from the reign of Henry VII.
...I had my bows bought me according to my age and strength, as I increased in them, so my bows were made bigger and bigger. For men shall never shoot well unless they be brought up to it.