All personnel in the Armed Forces want and need a good knife. It has been in our kit since the first armies marched into battle... and it will always be there.
Those in a non-combat, support type role can get by with the daily tasks by carrying a Swiss Army Knife or a Leatherman type combi-tool... soooo many choices here.
Those in combat roles can carry the same Swiss Army Knife or a Leatherman type combo-tool but also include the additional sheath knife for G/P or "General-Purpose" use... for those of us that venture into harms way.
These knives should have clip-point blades from 7 1/2" and longer, have a double guard... have micarta leather or other natural handles... and should be strongly constructed and come complete with a good sheath. Some
examples from cheap to expensive... A KaBar (cheap), Randall 14 (moderate) or Bagwell (expensive) will fulfill the role... again, lots of choices here (...do your research). A word of caution (from my old SGM)... stay away
from any serrations/saws on the spine of your G/P sheath knife, as these can be detrimental in the employment of the knife... for combat purposes.
Dagger types (Gerber, F/S, V42) are cool and historical, but are limited only to sticking people... and that's it. Which most of you will never do anyway... if you are lucky. A G/P type blade will serve you far better.
Finally, some of us will need specialty cutting tools like machetes, smatchets or khukris... for specific tasks in rough environments.