 The "Mesmer"
This is the ability to hypnotize humans, fairies and possibly other creatures (although mesmerising another fairy is illegal according to the fairy book); and is available to every fairy, even the ones most drained of magical energy.Some humans are more resilient to the mesmer than others, and wearing a pair of mirrored sunglasses makes you unable to be mesmerised, because the magic is reflected away.Shielding
This is a bit of a misnomer, as it actually is simply a cloaking device (although it is not referred to like this in the series) When a fairy shields, they simply increase their heart rate to vibrate at such high speeds that the human eye cannot see them.