So.. even in their write-up, it's totally a thing where some people try to collect it. That must mean it is special! How about we make it special?
While small folk have the ability to make others small already, I'm suggesting this that sets pixies/nixies apart a bit more from Fae without further stunting what they can and cannot do.
Pixie Dust- either an innate ability or a spell
A pixie/nixie can gather up the dust from around themselves and either fly it over someone or something or blow it upon them and make them float. This float goes no higher without aid than 1ft per nixie/pixie level. It is floating, meaning it is not controlled flight and resembles anti-gravity, often used in cases of mischievous sport or for a nixie/pixie to use their own flight to pull an object or shrunken person along with them with weightless ease. Very useful for moving dollhouses!
I suggest this because by using their dust in such a manner, it could be a way for a nixie/pixie to ward off danger, making to float in place while they take flight and flee. Unlike Fae, nixie/pixies do not have access to any actual combat spells, nor can they even wear armor to protect themselves or take classes which could allow for better defense. In short, you can squish a pixie with flick! But at least this would give a better means for play and a mechanic allowing for them to flee. I'd love any thoughts/insight into this. It need work and clean up, and a better mechanic formula.. but it's a start!