Have you ever had a dream involving flamethrowers? In a dream, seeing or using a flamethrower represents harmful words said by you or someone else. These harmful words are the fire that can do irreversible harm. For example, if someone uses a flamethrower to burn you, the nightmares are about a plan against you. More information about thorough interpretation may be found here.
If you use the flamethrower gun to burn the grass in your dream, the flamethrower is destroying his bridges and ties with the people around him. The damaging comments are dumb and uninformed and will have a long-term impact.