Yes Londron broil is not a cut of meat, but is a fine name for the procedure for cooking meat which does not come from the loin area and is not ready for instant grilling or broiling. The marinade also imparts flavor into other wise non marbled meats. London broiling is one of the most common ways the average family cooks and serves beef so the phrase is neither meaningless not an indication of the inability to serve fine cooked meats.
London broil can be from top round, bottom round, eye round, flank , tri tip, even shoulder areas.
London broil is usually marinated at least a counple of hours with some type of acidic base to break down conective tissue, it can even be pinned. London broil is than quicky grilled/ broiled and slice across the grain with the knife held at a 30 degree angles in thin strips, perfect for a 8-9 inch carving or slicing knife.
Swissing a pice of meat is a production technigue for taking meat with high degree of connective tissue from exercised muscles and eith pounfing ith a cuber mallet or pinning ( running it through a machine with many short needles) to break down the connective tissue to make it mmore tender. The meat is usually the braised. To itilize the many cuts of meat a steer offers different techniques need to be employed to make the meat tender enough to eat.
BTW Boiling is not a correct way of cooking meat as the tendons/ connective tissue shortens up and actaully makes it toucher.
Roasted meats like turkey and most roasts are fine for these smaller carving/ slicer knives also. Same with briskets and corned beef.
One of the most important things about using any tool is to match it to the job, This is also true with knives. With a knife the ability to control it is of prime importance. The use of a knife larger than necessary in the same category can lead to decreased control and not as exact a cut. It is for this reason I have a 7" chefs knife, a 9" ches knife and a heavy 11" chefs knife. I have two types of boning knives one fexible on for fish and a stiffer one for meats. Carving I have three, a 8 inch on for London Broil, small roasts, turkey, chicken, salmon sides, and 10 inch for larger roasts, and finally a 12 in wustaff
The long carving knives are generally pulled for use with whole roasts like 22 lbs bottom rounds, 15 lb tops, prime rib etc. Most family homes do not serve these usually , however restaurants do.
Wusthof Classic Ikon Hollow Edge Flexible Salmon Slicing Knife, 12-inch | cutleryandmore.com