How do I handle an opponent who loses it at me, and what if I'm the one who keeps arguing with referees?
Stay calm, let the referee deal with the other fencer, and limit yourself to one polite question per call you disagree with. You cannot control how someone else reacts, but you can refuse to join in. Fencers who stay steady while an opponent melts down usually win that bout, and fencers who fight referees usually lose the next close call. The rules back this up: a fencer disturbing order on the strip earns a red card, threatening or insulting an official is a black card, and an offense against sportsmanship can also be a black card. Anything you do in return gets judged by the same rules.
Accidental contact is part of fencing. Bell guards collide all the time, and in sabre, where both fencers often attack at once, hands and guards meet hard. If someone gets hurt, stop, check they are okay and apologize once. An apology is not an admission that you did something wrong, and you do not owe a second or third one. If they yell, stand quietly at your line and let the referee manage it. At the club, raise it later when everyone is calm, or ask the coach to step in. Taking a break from fencing that person is completely reasonable.
Gamesmanship is a gray area. Retying a shoe, testing a weapon, swapping a blade or taking an injury break to kill your momentum are common and often legal. Referees can card real stalling: delaying the bout is a yellow card, and stopping for a medical reason the doctor does not confirm is a red card. You cannot make them stop, so use the pause yourself. Walk back, breathe, remind yourself what has been scoring, and be ready the moment the referee says fence.
If you keep arguing with referees, change the habit rather than quitting. The rules let you politely ask the referee to explain the action, but only after they have made their decision, and they do not have to change it. Ask once, calmly, what they saw. Then accept it and adjust, because that referee's reading of right of way is what scores today. If you are in your first year or two, most disagreements come from misunderstanding right of way, so watch video with your coach. And if a parent or coach is winding you up from the side, ask them to save their opinions for after the bout.