So, on the runes front, you named the only 3 that do anything of note, out of a pool of what, 40? The rune which gives dmg for no armor is a fun, gamble heavy, gimmick rune that is currently used by one niche build (range beserker). So if you're not going ranged beserker, and you're playing saga, runes are dogshit.

Invulnerable for 2s helps you immensely when fighting late game jotunn that 1 shot everything.

The extra mana with invulnerable dodge rolls means you brain afk auto attack and roll at the last second. You then splurge the full 4 mana bar you've built, then rinse and repeat.

You dont have to give a damn about rotations as a warrior or what might hit you, you just dodge when they do something. Every other class has to pay attention, weave in and out, and ultimately lose dps + mana per second.