Someone brings this up in nearly every thread discussing Determination. I see your main is listed as Conjurer, so I have a very simple test for you: Go into town and cast Regen on a low-level crafter (they will have low Det, likely 30 or so). Make note of the healing tics. Then cast Regen on yourself with your 200+ Det.
Pretty sure the healing tics will be the same.
Determination is a stat to directly increase your output, be it weapon skill damage, spell damage, healing, or auto attacks.