It depends on how you want to play. Nightblades are stealthy and benefit from a lot of stamina and critical damage bonuses, which synergizes well with the Bow and Dual Wield. Templars do have healing abilities, but keep in mind that if you want to stick with Bow, you'll probably be investing a lot of points in stamina which limits you to a primarily DPS role with a smaller magicka pool for emergency heals. If that's what you're looking for then great. If you want to go Templar because you're interested in healing, I'd recommend choosing a restoration staff over bow as your ranged weapon and investing your points into mostly magicka.

Both Templars and Nightblades can shine with bows. It's all about play style.