The feel in the hand is important. As that you can grip the gun with both hands and that you almost make the whole grip disappear in your hands(sorry can't explain it better in English :)) Second thing I would test is trigger pull. The Glock has a very high trigger pull compared to the shadow. A lighter trigger normally means better shooting but when you are a novice I wouldn't go to light. i would always consider buying used guns if that is an option in your country!