Third attempt
Could it be,
A sound
With jolt or breath, I dine with death
sound can be formed by jolt or someone talking, breath, and dies off quickly
Unwanted by most, light I can boast
Most people don't want to listen to a lecture and I would bet even less want to hear someone boasting about light
Lecturn or wall, tethered, not all
You lecture at a lecturn and sound echoes off walls but they are not connected
Your will or my squall, the point of my call
Talking can be your will and squall and call make sounds
Second attempt
Could it be,
A gun shot
With jolt or breath, I dine with death
An accidental shot or someone yelling the order to fire, causing death
Unwanted by most, light I can boast
I don't think most people want to be shot and a muzzle flare produces light
Lecturn or wall, tethered, not all
There is a possibility of being shot anywhere, it doesn't matter if you are in class at a lecturn or in a back alley against a wall.
Your will or my squall, the point of my call
shooting someone could be meditated, your will, or the sound of the gun going off, my squall.
First attempt
Could it be,
Electricity
With jolt or breath, I dine with death
Electricity can jolt you and bring you back to life or it could kill you if too much of a jolt
Unwanted by most, light I can boast
Most people don't want to be shocked and electricity can produce light
Lecturn or wall, tethered, not all
Electricity is not tethered to anything
Your will or my squall, the point of my call
Lightning forms in storms, or squalls