The Ankh Shield kind of sucks. For the amount of effort it takes to obtain its ingredients, it isn't much better than the Obsidian Shield because all of the debuffs it prevents aren't very common.
Let's fix that.
Eater of Souls, Devourer, Face Monster, Crimera, Blood Crawler: Now inflict Weak and have a chance to drop Vitamins
Wall Creeper: Now inflicts Poison and has a chance to drop Bezoar
Shark, Sand Shark (and variants), Blood Zombie, Drippler: Now inflict Bleeding and have a chance to drop Adhesive Bandage
Granite Golem, Granite Elemental, Stone Golem, Paladin: Now inflict Broken Armor and have a chance to drop Armor Polish
Sand Slime, Sand Elemental (tornado), Antlion (spit): Now inflict Slow and have a chance to drop Fast Clock
Mushi Ladybug, Anomura Fungus, Spore Zombie, Spore Bat, Fungi Bulb, Fungo Fish: Now inflict Confused and have a chance to drop Trifold Map
Ghost, Illuminant Slime, Chaos Elemental, Illuminant Bat: Now inflict Silenced and have a chance to drop Megaphone
Slimer, Crimslime: Now inflict Darkness and have a chance to drop Blindfold
Demon, Black Slime: Now have a chance to drop Blindfold
Ice Tortoise, Snow Balla, Mister Stabby, Snowman Gangsta: Now inflict Chilled
Desert Spirit, Red Devil: Now inflict Cursed and have a chance to drop Nazar
Bonus:
Flying Snake: Now inflicts Venom
Pigron: Now inflicts Feral Bite
I have mixed feelings on this... But I see what you mean.
On one hand, yes the Ankh Shield
is too difficult to craft for what it provides.
On the other hand, it's not a bad accessory at all, it's fantastic for general purpose exploring, particularly in places where annoying debuffs are common like the Jungle, the Dungeon,
or the Snow Biome. It also has an interesting synergy with Feral Bite, it doesn't prevent the debuff but prevents all the random debuffs Feral Bite normally inflicts,
turning it into a 20% damage buff with only a small life regen penalty.
With that said however it's still only "good", not great, and definitely not worth the effort unless you really want to go full tank or really want that 20% damage pseudo buff.
It's main weakness is that it doesn't prevent a lot of the really nasty lategame debuffs like Electrified, Frozen, and Distorted.
It's other weakness is it's long, grindy crafting tree.
While some of it's ingredients are pretty easy to find like Armor Polish and the Bandage from post-Plantera Dungeon, other's are a pain to grind like Vitamins and the Nazar.
Bumping up the drop rate from 1%/2% to 1.5%/3% might not sound like much, because it isn't, but that's still a 50% increase, it would help.
Adding more enemies that drop the items as well would be good, some are no-brainers like Demons and Black Slimes who inflict the debuff but don't drop the Blindfold,
or the Brain Scrambler that inflicts confusion but doesn't drop the Trifold Map.
Making more enemies inflict debuffs and drop the respective item could work too, but do be careful which enemies you give such treatment.
As for buffs to the Ankh Shield itself?
First I would make the Bezoar also give immunity to Venom, the Bezoar is now also dropped by enemies that inflict Venom, there's only three of em' in the game but still,
would be nice for Underground Desert and Black Recluse farming.
Second is to make the Hand Warmer(not Hand
Warmers apparently even though there's two of them) part of the crafting tree, it's now dropped by all enemies that inflict Chilled and Frozen, which is surprisingly few? Probably make a few more, I can't believe I just said that... Anyway, the Ankh Shield now will gain Immunity to Frozen and will no longer gain it's chilled immunity from nowhere.
And third, I would just give the Ankh Charm a niche immunity or two like Blackout and Distorted, I know what I just said about immunities from nowhere but, c'mon.
No one likes Distorted.
A bit more defense wouldn't hurt either, it was a staple of most full tank builds, at least before Frozen Shield and Hero's Shield got added.