Easily my favorite "later in life" tool discovery. I don't think I even heard of a needle scaler until age 30, and even when I first bought one, never imagined how useful they were. There are so many jobs where there's just no acceptable substitute for that tool.
Whether it's removing rust and paint from an old implement, removing badly caked on grass swarf from under a mower deck, or slag from a welder, the needle scaler can get it done as gently or roughly as you need. It helps to have a few in different sizes, if your compressor can support the big'uns.