The single guard assumed primarilay to protect from lateral cuts or to chest, with the arm across the body, closing the high inside line.
Quarta guardia
Agrippa's left side guard.
Quarte 
The small sword, transitional and modern fencers name for the guard which closes the high inside line. 
Quarte outside
Seventeenth and eighteenth century name for sixte, as sixte was not common until the late eighteenth century.
Quarte over the arm
Seventeenth century term for a disengage from quarte into a thrust delivered over the opponents arm.
Quillion
A Renaissance term for the one or both branches of the T shaped cross guard on swords, which prevents the opposing blade from sliding into the hand.
Quillion bash
Parry followed by throwing the opponents blade off line with a strike from the quillions
Quillion block
Block of metal from which the quillions etc. stem.
Quillion dagger
(Poniard) A dagger with wide quillions, popular from the thirteenth through to the eighteenth century. Often used in conjunction with a sword.
Quinta
The fifth guard position in double fence, with the rapier out in front of the body and covered by the dagger at the forte.
Quinte
a/ The modern fencing sabre parry that protects the head from a vertical cut. b/ The fifth thrust, or parry of eight taught in the French school.