Sword: Through its nose, it sucks in the emanations produced by people and Pokémon when they feel annoyed. It thrives off this negative energy.Shield: It sneaks into people’s homes, stealing things and feasting on the negative energy of the frustrated occupants.
Prof. Lotus' Notes: My guess would be this is a portmantaeu of Impid (inclinded to be mischievious / naughty) and imp a small devil or sprite found in Germanic folklore described as mythological beings similar to a fairy or demon which could attribute to it's typing being Fairy and Dark