Had the Amethyst Collar (or whatever it is actually called) and was going to use it on Ascian.  However, I clicked to use it not really thinking about the fact that I should be adjacent to use a collar.  So I clicked on Ascian and it told me that I was out of range to use that item.  Ok, no problem.  So I moved adjacent and went to use it properly this time and guess what?  The collar, according to the game, had been used up so no more collar.

So my suggestion would be to either notate that in the collar's description or make it so that you are not penalized when an item is used incorrectly. 

Now I'm not sure if this happens with any other items so in case it does I hope that it will be made more apparent to the player or changed just a bit.