Knives are amongst the first primitive tools known, and have since been made from every material from flint and obsidian to high-test titanium and advanced composite plastics. As a result, knife fighting comprises an ancient and respectable family of combat forms known around the world.
Your Desert RangerPrivate fresh out of Ranger Center might want to equip his Knife if he or she is trained and has a modicum of Strength, Luck, and Agility. With extremely high Strength, Luck and Agility, and very high Knife Fight and Brawlingskills, it is very possible for a character to take on hardcore enemies with knives and beat them soundly. However, in such endeavors, it's usually faster still to just give the character a Proton Ax and watch the carnage.
1 - Weapons in this category do not have a governing skill; melee weapons are distinguished from regular items by damage they deal (3d6 as opposed to 1d6 for items)