Unlike the majority of sideshow tricks, there really is no secret to sword swallowing that makes it appear more impressive, dangerous or painful; you just have to do it.
It is a fairly risky act with ancient roots, and most famous sword-swallowers have had one or two notable injuries.
In the 1890s Miss Victorina (Kitty Fisher, a native of Berlin) swallowed swords in her act along with her husband Kar-mi.
Kar-mi would swallow a loaded gun barrel, and while it was down his throat, would shoot a cracker off a man's head, while Miss Victorina was said to have swallowed a record 16 swords at once around the turn of the century.
In 1899 the Victorinas put out a "Text Book On The Art of Sword Swallowing - Explaining How To Do It Sixteen Different Ways" with some mythical tips on how to swallow swords, some written in an untranslatable ancient script! I would love to get my hands on a copy...
The Boston Herald of December 28th, 1902, described Victorina's performance:
"By long practice she has accustomed herself to swallow swords, daggers, bayonets, walking sticks, rods, and other dangerous articles. Her throat and food passages have become so expansive that she can swallow three long swords almost up to the hilts, and can accommodate a dozen shorter blades." On one occasion, while sword-swallowing in Boston, a sword pierced a vein in her throat.