Ashe makes a pretty good Bushi because katanas take strength and magic into account. A white mage/bushi combination is good for Ashe because the magick lore licenses from the Bushi class allows her for high healing/magick damage output as well as high katana damage.
I don't think Bushi/WH is that good. You get just 3 Magick lore licences a and healing. Healing is good, but not for damage dealers. I would give bushi job with Heavy Armor, more strenght is better. Knight is good combo. Heavy Armor, shields (for Khumba). And knight gets mystic armor. Excalibur plus White Robe is one of strongets combinations. Hits for 40k are always fun.