Metal weapons are abolutely fine, barbarian levels just give proficiency in all martial weapons, while druids normally get a more limited selection, but metal armour & shields are still in violation of the druidic oath, unless you have Force of Nature, found in tier 5 of the nature's protector tree.
Dragonscale armour is fine, it's not metal. There are also some other armours (annoyingly the heavy bronze dragonscale armour in the Hruit's set is copper so a metal, rather than actual dragonscale) that have non-metal material types - incidentally the level 6 core enhancement in nature's protector gives heavy armour proficiency so that can be an option too, you'll trade more AC & PRR from that for better dodge potential in medium.
If you have the feydark illusionist tree, the weapon imbue from illusionary weaponry makes weapons & shields immune to damage by changing their material type to force which hey, isn't metal!

You'll need to cast it, then unequip & re-equip the shield each time but it'll let you use metal shields without breaking the oath, though won't do anything for armour. The second core ability in the divine crusader tree, confront any foe, does something similar but converts the weapon & shield to light as the material type, but that'll require level 23 & 6 points spent in the tree.
As for what named ones to use while levelling epics, terrorweb chitin is solid, though tbh I usually just roll with the hardened hide from good intentions until i hit high epics & can switch to one of the ml29/30 ones.