This trick is very basical. I think almost everyone already know how to do it, so why put it as a utility? Well well, anyway... this utility is so basic and so easy, yet so usefull. This is one of the most usefull tricks in the game, as long as you can combine some units correctly. You did that good in this utility. Man at arms + horse = knight. The only thing that's needed more is a white horse, although AoK doesn't have that, so you can't do anything about it.
Make some more advanced utilities, or at least add some text in the description like: "This trick is very basic, but very usefull. For those who haven't played this game for long, this can be very usefull IF you like to design maps of course"