Solar Buckler and Skull Shield are exactly the same card. That seems like a pity, and I've also noticed that we don't have a cheap, no-frills-added 2-damage blocking shield in the upgraded set anywhere.
Therefore, I'd like to humbly propose that Solar Shield upgrade not into Solar Buckler, but into Corona Shield: 3
for 2 damage blocked, with no extra frills or abilities.
Thoughts?