As it is, every 10 in a weapon skill gives you an extra BAB and allows you to choose a Weapon Proficiency perk that gives another BAB, essentially allowing you to jump 2 BAB every 10. This is sorta rough, because your BAB stagnates for roughly 10 levels before suddenly mountain-ing up in power. Then it stagnates again for another 10 levels before another mountain boost in power. It’s very un-smooth.
My suggestion is that we instead have Weapon Proficiency Perks at each 5 interval, skipping the 10s (i.e. 5, 15, 25, 35, etc.) so we’ll have the same amount of Weapon Proficiency Perks but the increases in power (when we account for every 10 ranks giving you a BAB) will be more gradual and smooth than not.