If you mean the foil, épée, and sabre used in modern sport fencing,

1. The foil is a blunt training version of the smallsword as used in the 18th century, and is of similar weight, balance, and length (the modern size 5 foil is about 8cm longer than the average smallsword in blade; the size 2 and size 3 are smallsword-sized). The modern pistol grip is not historically accurate in that it wasn't used on smallswords. The French grip was also developed for the foil. The Italian grip (rare in modern fencing) clearly shows its ancestry from the smallsword, so could be called the most historically accurate of the modern foil grips. Originally, it was very important for the foil to be "historically accurate" (i.e., it had to closely resemble the contemporary sharp smallsword) since it was a training tool for learning to fight with the smallsword, and except for the modern grips that differ from smallsword grips, it is still fairly historically accurate. Many (but far from all) smallswords had a knucklebow; the fencing foil does not.

2. The épée is a blunt version of post-smallsword duelling swords - the épée d'combat or duelling épée of the late 19th century through to the mid 20th century. Length and weight are similar. Again, "historical accuracy: was important. Grips of the épée d'combat were similar to (and based on) the French foil grip. The épée d'combat is not as well-known as the smallsword; some examples can be seen at https://fencingclassics.wordpress.com/2011/12/21/weapons-eight-dueling-epees/

3. The fencing sabre developed as a sporting and duelling weapon, and has little relation to military sabres (and what there is is largely late military sabres which were influenced by the development of sabre fencing as a sport and other sport fencing). One of the founders of modern sabre fencing, Giuseppe Radaelli, a 19th century Italian fencer did much development towards the modern fencing sabre. He was a military fencing instructor but it is to be noted that the fencing sabre is not simply a blunt safe version of a military sabre for training.

Also, how would a modern day fencing expert compare to a master swordsman of the past?

Aldo Nadi, an early 20th century Olympic fencing gold medallist, fought a duel with sharp swords, commented that "In a duel, the fencer is compelled to execute an ultra-careful form of fencing, which, indeed, is an almost unworthy expression of the science he knows. No matter how courageous and great, the all-out movements with which he nearly always scores in a bout would be unthinkable in a duel, because it's far too risky." (from Aldo Nadi, On Fencing, quoted in J. Christoph Amberger, The Secret History of the Sword (1999), which discussed the relationship and differences between fencing, dueling, and other swordfighting). The rules are different, the risks and attendant stress are difference, and some adjustment would be required by either the modern fencing expert or the past master swordsman. Nadi's duel provides a suitable comparison - his opponent was an experienced duellist, with 5 successful duels already. It was Nadi's first duel. Nadi won. A lesser fencing expert vs a better-skilled duellist could have turned out differently.

Comparing a swordsman from the days before the smallsword, or from outside the Western sphere where it was used would require even more adjustment. Modern fencing experts train a lot, and train well, and train with very skilled training partners - if the modern expert and past master were to compete under modern fencing rules with modern fencing weapons, the modern expert should do well.