BTS is always a worthwhile choice if you use swords on a regular basis; despite its lack of elemental and fire, it will generally hold up better than the Dragon Scale in most scenarios, due to Dragon's lack of normal defence, and since most things do normal damage... GOwlite is almost always a better option than Dragon Scale, the only exception being if you're running C42 Danger Missions.

It goes like this:

-In T1, everything deals just normal damage.
-In T2, everything deals split normal/specialised.
-In T3, it works a bit like our weapons do.

What do I mean by that? Have a look at a brandish upgrade, for instance. Glacius deals a 50/50 split of normal and elemental damage. When a wolver bites you, it deals some normal damage, some piercing. You'll notice that when it happens, some red bars spout up from you and some yellow ones do. Those show how much normal and how much piercing damage you took.

Projectiles and bombs are 100% specialised. Again, look at guns and bombs. Cryotech Alchemer does a load of elemental damage and nothing else. When a polyp shoot you, it does only piercing damage. Don't believe me? Try for yourself! Just go block a zombie attack with Volcanic Plate and Dragon Scale, see which one lasts longer. For the giggles, also try blocking with Swiftstrike Buckler and take note of how Dragon Scale didn't last any longer.

Almost EVERYTHING in tier 3 deals normal damage, just not 100%. Here are sources of normal:
-EVERY melee attack. Zombies, kats, wolvers, jelly cubes, lichens, overtime devilites, retrodes, mecha knights, lumbers and probably a bunch more.
-Gremlin thwackers and Trojans among possibly others do pure normal damage.
-Wheels in FSC, probably a bunch of other stuff.
-I suspect puppy rockets to do at least part normal, as well. Volcanic Plate tanks them like nothing.