On bits, with regard to control of a horse, a bit isn't the key thing. A horse's innate response to pressure, any pressure, is the key. So, something as simple as a noseband, or leg pressure, or even just energetic pressure will cause a horse to respond. A bit is a coarse instrument, in actuality. Directing or trying to control a spooked horse will intensify their need to escape; they are prey animals and keeping them still when they want to move doesn't work--trust me on this.
As for tamer/tamed/domination...uh, no, not really. It's a partnership, through and through. The horse's physical might and grace, the rider's desire to attain a specific goal. Very few horses tolerate an attempt to dominate them. They'll just blow right through that with their superior strength and either flee or lose respect for the one who tries to outwit them in this fashion.
Ehwaz is about trust, merging, complimentary beings moving as one. I wrote about it at the Temple blog, with respect to one special horse, Maple. The entry is two pages with images, but I think you'll get what I'm trying to say if you have a look. Force and domination only made this animal more unwilling. Listening and asking, respecting her, is what allowed us to be united. while we have intellect on our side, harshly or heavily applied you will either crush the spirit of the horse and render him unfit to give 100% or drive him away and make him wary of ever joining up with a human. It is a very delicate dance.