Adrian Lister reviewed "The Big Cats and Their Fossil Relatives" by Anton and Turner (Nature, 1998, 394, 334). He comments: "The function of the sabre-toothed cats' distinctive flattened canines, which could be as long as 28 centimetres, has been much debated. Turner and Anton suggest that they were too delicate to be used on moving prey."
I have a plaster saber-tooth skull in my office. Janet -- 16 years old, owner of her own web site, and into wearing dog collars and skimpy clothing -- commented that the teeth were far too large to be good for anything. She hadn't read Nature but is pretty good at repairing car engines. I think her intuition about the teeth is accurate.
We primates -- perhaps just us male primates -- note the teeth and react with primate avoidance with thoughts of killing, blood, and pain. Avoidance is a useful tactic when you have puny legs, no claws, and teeth better suited for grinding things already dead than for making things dead in the first place. It's a particularly useful tactic when there are cats. However, our adaptations for fear and avoidance can mislead us. Likewise, our adaptations for using tools and seeking "functions" in other creatures' tools.
Those teeth were probably of greater value in sexual selection and perhaps intimidating other male tigers than for actually cutting throats. The size of the teeth may have been limited by homeostatic costs such as the mechanical disadvantages that occur when a long lever encounters moving, resistant flesh. We monkeys would use the teeth, once detached from the cat, for making holes and ripping other creatures and for attracting female hominids but not for attracting female cats.
Geoff Miller and Lister are both at University College and perhaps ought to get together. Geoff is becoming the world expert on sexual selection and ought to be fascinated by the cat's teeth. The challenge for sexual selection theory is why some cats grew big teeth instead of longer tails? Sensory mechanisms easily could "pull" an exaggerated feature along, once it became a salient item for the female to notice. Perhaps any change towards larger, brighter, or livelier, will enhance attractiveness? It seems to go that way with teenagers so long as the change draws attention to symmetry, relative waist size, and liveliness in females and to wealth, strength, and dependability in males.
Incidentally, Anton and Turner's book is published by Columbia Universwity press and lists for $46.