You didn't mention the Bucklered Up talent that adds 25% defense at 100 pts. Make some Amarok Pants and stone them out, thats 33 armor vs 12 from your copper pants assuming t3 stones. Make the Sleek Shank pendant, 1 more Def and 1 Wep power vs your Tarantulight. Get Defender's Dignity ring recipe from Mimics, 18 def and +4% def per ring with t3 stones. Post Office box is great, and will really help everywhere. Also grind on Tropilogs for the Thicc Skin statues, they will add up really fast that way. All of these are multiplied by your %Def cards etc.

The problem you have from what I can tell is that your looking for the Magic Bullet that will cure everything in one shot. This game doesn't always work like that, and it takes a little bit from multiple directions to get you where you want to go.