Why doesn't fencing have weight classes or height classes like boxing and wrestling do?
Fencing has no weight or height classes because body size does not decide a bout the way it does in sports where you strike, throw or pin another person. You score by landing the tip or edge of a weapon, and a touch that sets off the light counts exactly the same however hard it lands, so extra mass buys no extra scoring power. There is no grappling and no pushing your opponent around either. The official categories at USA Fencing and the international federation are age and sex only: youth age groups, cadet, junior, senior and veteran brackets, with separate men's and women's events at the national and international level.
Height is the obvious worry, and it is a trade, not a free advantage. Every adult uses the same maximum weapon length, 110 cm for foil and épée and 105 cm for sabre, whether they are short or tall; only the youngest youth events cap the blade shorter. A tall fencer reaches farther, but also offers a bigger target, recovers more slowly from a deep lunge and gets awkward once an opponent slips inside the point. Shorter fencers tend to move faster and win at close quarters. In the Paris 2024 Olympic men's épée final, Japan's Koki Kano beat France's Yannick Borel 15 to 9, even though Borel is around 20 centimeters taller.
There is a practical reason too. Fencing is a small sport, and splitting fields by weight or height on top of weapon, age and sex would leave most local events with a handful of people in each group. Skill already gets sorted another way: fencers carry ratings from A down to E (U for unrated), and many tournaments offer events restricted to lower-rated fencers, so a newcomer is not thrown straight in against the strongest people in the region.
What this means for you is simple: your size shapes your style, not your chances. Tall fencers should learn footwork and close-range work early instead of leaning on reach, and short fencers should make movement and timing their weapon. Pick the weapon you enjoy, and if you are much bigger than your training partners, take extra care to hit with control.