A year ago I outlined this issue, and it's still not fixed. Can you please take a look a this.
Weapon Attacks and Direct damage skills, use Master-at-Arms to modify the Glyph damage done,
Wall of elements, Barrage, uses Thaumaturge, when the weapon enchant procs.
If you specced low on Thaumaturge, and start fight with Wall of elements for example. The Weapon glyph will proc at lower damage.
Weapon damage procs should always use direct damage,
Possibly Thaumaturge could modify Secondary effects like poisoned, burning etc.
https://forums.elderscrollsonline.com/en/discussion/comment/5452330#Comment_5452330