QUESTION: Someone told me that "-ing" words are weak and should be avoided. I've never heard of this rule. Is this common knowledge among writers? Have I missed something somewhere?
Pick up the average book on writing style or editing, and you'll see that "-ing" phrases have a bad reputation.
As part of an introductory phrase, it's overused and prone to misuse.
Misuse -- Picking up the gun, she walked across the room and shot him.
The introductory phrase happens at the same time as the verbs in the sentence so the sentence above is impossible.
Proper use -- Grasping his shoulder, he fell.
Too many introductory phrases used closely together also weaken the writing. They slow the reader down so he’s mentally plodding through your prose.
I'm prone to using them to avoid having too many sentences beginning with "he" or "she." That's where rewriting the rewriting comes in.
The other common overuse is attaching the "-ing" phrase to a dialogue tag.
Overused— “I don't like it," she said, shaking her red correction pencil in my face.
Better use— “I don’t like it.” She shook her red correction pencil in my face.
Introductory phrases have their value if used properly and infrequently. Just avoid the evil that is -ing.