I read a post (months ago I remember o.o) where Nick said that they had plans to bring Darkfang Shield into our "not rare and ridiculously easy to get" part of the arsenal which every other item in the game is currently sitting in. So basically, it is expected that Darkfang will no longer be rare and be a regular old shield with no value anymore (when they make Darkfang no longer rare, it will get a 5 star version and the stats will be reworked to not be identical to a Grey Owl, to clear up any possible confusion)
Also, likely, the Zee Core will be brought into the "not rare and ridiculously easy to get" category some time in the future when sleep is implemented.
Currently, I usually have stuff to do in my free time hunting for rare items for hours and such in video games, however it seems I don't have any rare items to do this with (not willing to farm a Darkfang Shield / Zee just to have it made not rare the next day).
So like, let's add more rare stuff to make up for this >.>
I think how the Darkfang Shield thing was rare and the stats it gave were great. This is because there is a shield, better even (Grey Owl), with identical stats. Rare armor / weapons should not be powerful, as that is not how this game should be designed. If anything they should either be A. Identical to, or B. Not as powerful as easy to obtain items. Or even both, "identical" but not as good (like Grey Owl vs. Darkfang).
Specifically, I don't have any good ideas. I guess like a rare Sentenza that is colored black / grey like the 3* antigua is colored, which shoots black bullets (and with a different namethan Sentenza of course).
Also, I would really like it if rare items had a chance to drop from a certain T3 MONSTER rather than just generally "all T3 treasure boxes" like the Darkfang (although there are claims of decon zone-only / thwackers dropping it). This way, it would encourage us to go to the Arcade more and encourage us to find a use for our crystals and actually WANT to change the gates to a specific theme.
I've actually had a few ideas for more 'rare' items like this floating around, now seems as good a time as any to put them forward:
Trojan's Blade: Acts like a Khorovod.
Ironwood Axe: Also acts like a Khorovod.
Trojan's Shield: Acts like a Heavy Plate Shield.
Almirian Spear: Acts like a Fierce Flamberge.
Phantom Blade: Acts like a Vile Striker (maybe without the poison?)