Displayed effect of basic ingot and etched ingot is the same. I.e. ingot(gold) provides 10% magick power, etched ingot (gold) displays the same magic power bonus. It looks like something was missed in the programming. No sober player will use 2x material to gain the same benefit.
I believe the text for these says they're more fragile but more magical, so would agree they should perhaps offer less durability but boosted stats
Currently, etched ingots are only useful for crafting certain items that require such ingots. I don't think the lack of a bonus is an error. However, I agree that a change is necessary; I was going to post feedback on this topic, but since there's already one, I'll comment here. I think these ingots should be renamed to 'refined ingots' rather than 'etched ingots', and these refined ingots should have a small stat bonus and be usable anywhere a regular ingot is required.