Looking over my inventory, I figure I should actually take stock of what gear I have for each realm and where I need to shore up. I'm actually....surprisingly good for synergy in the common realms? I'm legit surprised by this.
FF1: 4+ armor. Who cares, it's FF1
FF2: 4+ sword, 4+ staff, natural 4 dagger, 3+ dagger.
FF3: Natural 4 rod, natural 4 staff, Diamond Helm (4* unique SB gear for Knight), 3+ light armor
FF4: Dark Sword, Ice Whip, Thunder Rod, Dark Gloves, 4++ dagger, 4++ staff, 4++ light armor, 4+ dagger, three 4+ robes, 3++ sword
FF5: 6* Genji Blade, 6* Sage's Staff, Crystal Helm, Genji Helm, 4++ helm, 4++ heavy armor, 4+ rod, 4+ Rune Axe (for all the spellcasting axe users...), 3++ light armor, 3++ hat, natural 4 hat, 3+ hat
FF6: 6* Gold Shield, Holy Lance, Burning Fist, Gaia Gear, Mystery Veil, 4++ hat, 4+ rod, 4+ thrown weapon, 3++ heavy armor, 3++ light armor, natural 4 sword, natural 4 dagger, natural 4 light armor, natural 4 heavy armor, 3+ dagger, 3+ helm
FF7: 6* Gold Sword, Organics, Shark, Tiger Fang, Turks Suit, Wutai Headband, Holiday Mittens, 4++ glove, 3++ bracer, natural 4 bracer, natural 4 sword
FF8: 7* Cardinal, Blitz Sword, Valiant, 4++ dagger, natural 4 hat, 3+ hat, 3+ dagger
FF9: Ultima Sword, Cat Claws, Oak Staff, Power Sash, 4+ dagger, 3+ light armor
FFX: Shimmering Blade, Celebration Dagger, Dusk Lance, Mage's Staff, 4++ sword, 4+ light armor, natural 4 light armor, 3+ sword, 3+ rod
FF12: Runeblade, Musk Stick, 4++ sword, 4++ lance, 4++ hammer, 4+ dagger, 3+ rod, 3+ rod, 3+ light armor
FF13: Peacemaker, Goddess' Tribute, Evil Lantern, Witch's Hat, 4++ glove, 3++ bracer, natural 4 bracer
FF14: Yoshimitsu. Who cares, it's FF14.
FFT: Chameleon Robe, Kaiser Shield, Mythril Sword.