Again I'm getting off track but what I'm getting at is wand movement and Incantations are crutches, you just need to look at silent wandless magic to prove that, no all you need is very active imagination, proper knowledge and willpower, oh, and a healthy dose of confidence in your abilities. If you don't think you can do it with certainty you can't, that's Neville's main problem. In this case, transfiguration is easy when you have all of that. Turning a desk into a pig is child's play as long as you know basic biology and let the magic take care of details, pair this with heavy willpower and a clear image and what do you know? my desk is now a lovely little pig that I called Porkchop. Wizards are by nature lazy and unimaginative, sure they have some nasty curses to boil blood or skin alive their enemies but they have to have someone invent a curse to do it rather than just force it to happen via transfiguration. With the right knowledge you can turn someone's skin to steel and root them to the spot or maybe change their heart to a parrot or their lungs to a dishcloth or if you're particularly devious turn their blood to water or maybe something that stings like bleach.