TL;DR
Let me start off by saying that I can see the logic behind why ZOS made the change to 1h enchants, and I even whole-heartedly agree with it. Having access to more than one full-strength weapon enchant on a single weapon bar was just too powerful. This gave dual wield characters a clear and unnecessary advantage over both staff users and 2h users.

I can even get behind their reasoning for the change affecting 1h and shield as well. The shield itself already has a full strength enchant, so giving the weapon a full strength enchant on top of that would result in the same problem dual wield had: access to more than one full strength weapon enchant on a single weapon bar. Shield enchants, however, can only use armor glyphs and are consequently a lot weaker than weapon glyphs to begin with. I suppose this is the reason ZOS chose not to halve these values as well.

What's concerning to me is that these changes were brought about to eliminate the possibility of running two full strength weapon enchants on a single weapon bar, yet 1h and shield (where this was never an option to begin with) suffered the same reduction as the problem area, dual wield. That being said, I don't think it would be fair to give 1h and shield a full strength weapon enchant on top of their shield enchant either, because that too would allow for more than one full strength weapon enchant on a single weapon bar.

So here is my proposition:

A new shield glyph should be introduced that increases the power of the enchant on the main hand weapon, up to the exact level of a 2h enchant at gold quality. This would be a glyph unique to only shields so that it cannot be abused on armor pieces.

The addition of this glyph would maintain the current restriction of having no more than one full strength weapon enchant on a single weapon bar while also giving 1h and shield the option of running a full strength weapon enchant at the cost of the max resources a traditional shield enchant would provide.

This would, however, create a slight inconsistency in that current shield glyphs are using standard armor glyphs, while this proposed glyph would require a sub category of shield glyphs to be created. Other than that, however, I feel this would be a viable and complete solution to the current state of 1h weapon enchants.