You don't need a strong left hand to hold the violin steady
The left hand guides the violin, it doesn't carry it. Here's how the jaw and collarbone take the weight, and why thumb clamping is a frame problem.
Posture & Instrument Hold
Standing and sitting posture, holding the violin on the shoulder without tension, and head/jaw placement.
Why Does Your Violin Slide When You Reach for the G String?
Reaching for the G string shouldn't drag your violin around. Here's how the left elbow and forearm keep the instrument steady while the hand travels.