As the name "first danger" suggested, the fighting style was about fast reactions to the first appearance of an enemy and being the first danger to the same.
The majority of drow scouting groups had at least one user of this style among them, wielding a hand crossbow with a sleeping poisoned bolt That individual's role was to react fast and shoot to incapacitate an enemy before combat really began.
The style taught fast reactions and the ability to draw a weapon quickly. As drow society was one in which vigilance was paramount, the basics of this style were part of the standard curriculum of every drow fighting academy. It was certainly useful at the start of combat, but, being almost useless in prolonged combat, users tended to learn other styles to give themselves other offensive abilities.
This style is based on the Improved Initiative and Quick Draw feats of 3rd-edition Dungeons & Dragons.