Throughout my experience i have found ashe with nice crit dmg can do alot more early game so that's why full in offense and the hp regen and magic resist + armor is good for the early survivability. Still you have to know what your doing with ashe to play her this way.

Armor penetration works really nice on ashe and the red ones give nice armor pen !

The mana regen, offcourse because i dont go mana items, the runes are all you need !

Cooldown reduction, volley is essential as also your ulti. More faster and have the ulti more chance you have to save a teammate or kill someone.

Crit Dmg Quintessence provide you lvl 1 harass so cool that even you will laugh, with your combo volley + crit you can easly take 75% health of your oponent and send him to base, and sure mid late game with some crit change items, u make all the difrence.