"Ing" the Merciless

QUESTION:  A published author told me that "-ing" words are weak and should be avoided. Is this right? 

Pick up any 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 do so the sentence above is impossible.

Proper use -- Grasping his shoulder, he fell.  

The verb and the introductory phrase can be done at the same time so it's correct.

Overuse -- Too many of them weaken the writing as any overuse weakens writing.  They also slow the reader’s speed so they can screw up the pace in scenes.  Think of them as bumps in the road that make the reader pause.  

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.  "I don't like it," she said, shaking her red correction pencil in my face.  

A way to avoid this and write a stronger sentence would be—  “I don’t like this.”  She shook her red correction pencil in my face.