Wow. That was very good. Here are a couple things to work on:
Sana was short and thin with long, dark hair.She was always remarkably beautiful, especially for someone who needed help to do such simple tasks.
Usually, it's not good to directly describe the character's appearance. Instead, describe characters like this. (I did not write this, this is from another website).
Iona Thundermist was a princess of the wood elves from the tips of her pointed ears to her delicately crafted boots, all five and a half feet of her. She dressed in long riding gowns of lambs wool, thin but warm for the season's brisk winds, their cool greens smudged with dirt from the road. Her long brown hair was tangled, but her green eyes flashed in her pale skin.
Nobody could possibly accuse this of not being clear. The problem is that the entire story has stopped to describe her. There is also a lot of information we don't need.
This also subtly conveys the message that she is standing still. Now, let's say she's barreling down at you on her horse...
"Ride you fools!" rang a clear voice down the mountain road. The party turned from their warm fire to watch the woman bearing down on them, twigs tangled in her long hair, her fine robes muddied and stained with horse sweat. "They are coming!"
"Wood-elf," Alric snorted, but whether it was the fire in her great green eyes or the silver circlet perched on her head, he took her word and leapt to his horse.
That coveys a nice amount of information, but it doesn't stop the story to describe her. In fact, it speed up the story.
You didn't go overboard nearly as much as the first example, but watch out for that.
The rest was very good, and you hooked the reader, no doubt about that. I'm looking forward to what this will turn into. Gah, I keep thinking that the girl is some sort of mage and the man's a swordsman. Curse those three hours of playing Fire Emblem befoer posting here. Anyway, keep it up!