mb can be confusing , im no expert.
You get 14% increase in dmg for every point in powerdraw. Just remember you need wpf in archery to match it aprox 14 wpf for each point in powerdraw.
And max 4 points in powerdraw above the bows requirements. Rusbow req. 6 means max 10 powerdraw. Hornbow Req. 5 max 9 powerdraw.
Play with the plan char tools to find the right mix.
Leveling and playing as archer can be frustrating, so many limitations. You are not really effective before level 30.
Consider using a crossbow instead, no requirements , hard hitting and accurate. And can be used by peasants ,even the arbalest.