Repertoire guides are not the best judge of a piece's difficulty -- you are. Never give a student a piece that you haven't played yourself. Otherwise you risk setting that student up failure.
I recently made this mistake. I gave a student Chopin's Fantaisie Impromptu. He wanted to play it. I knew it, of course, but had never played it myself. So I gave it to him to learn. I had, in part, based my decision on the information given in a teacher's repertoire guide that I sometimes refer to, which placed it on the same level as Mozart's d minor Fantasie, and Brahms' Intermezzo opus 118, no.1 (both of which this student had played). As I learned the piece myself I realized that from a technical perspective, this is patently bogus. The Chopin presents numerous technical difficulties the others do not: the four-against-three rhythmic figures, the rapid tempo, the difficulty of playing on the black keys, the broken chords of the left hand. Alas, the piece turned out to be much too difficult for my student to handle successfully. It was an amateur mistake on my part --
but a lesson learned.