Not sure if it's worth crafting the whole set but the harnesk probably is though. That 50% pierce resistance could be useful against 2* draugr/skeleton archers in Swamps and deathsquitoes and starred fuling javelin throwers in Plains later on (at least until you can craft padded).

As for the mask, you're probably better off with using the poison resistance mead instead since resistances don't stack and the mead actually gives you higher poison resistance than the mask (75% vs 50%).

So for Swamps, you could probably go with iron helmet and greaves + root harnesk. If fully upgraded, should be enough to even skip silver armor and go straight for padded. Could just craft the wolf/lox cape for the frost resistance.