Meek, sensitive characters shouldn't scream or suddenly pull out Ninja weapons unless it's a comic piece. Gender, place, time, dress and manner of characters should all go together to support good characterization. Physical descriptions are appropriate to the piece. A viewpoint character should not be able to describe himself, unless it's integral to the plot. Physical description of viewpoint characters can be done indirectly, by the reactions of others to the character and the character's own interaction with the world of the story.
Omniscient narrators are pretty much on the outs in the current publishing world.
The omniscient narrator hops from head to head, from scene to scene and place to place and there is no single point of view or voice, other than the author's. The first-person narrator can only tell what he experiences and knows. This can be a powerful, but also a limiting voice. The reader becomes aggravated by the character, and generally quits reading. This is the most common narrative style used in novels and short stories.