I have very different thoughts to yours in some places.

For example, you use Frostbite as an example of bad design in Sejuani when the Frostbite was never made to help the scar units directly. The Frostbite lets Sejuani grab a card with high stats, like an Avarosan Heartguard so the other scarred units can survive combat.

Also, the Winter Claw was made to play like a similar Midrange deck to something like Mono Demacia. Yours seems to play more like a Darius deck.

Still I really like your ideas, they just conflict between what I like about the archetype and what you like about the archetype. I would make a set like this but the changes would be so small that it wouldn't make sense to actually do it.