Dwarf refers to a person with one of several varieties of a specific genetic condition called dwarfism. A dwarf has disproportion of body parts. This is generally caused by a genetic or nutritional disability. Any adult human below the height of 4'10 (147 cm) is considered a dwarf.
One Piece has a great story and does not have a lot of filler episodes.
In my opinion, it is superfluous filler to make one sound more important. That being said, I would recommend not using the phrase at all. While we're on the subject, at this point in time, it is a very good question. However, it is what it is, and I'm very glad you asked that.