There seems to be a general consensus that Cannith crafting is mainly useful for twinking low level alts. The situation is not totally dire, however, and there are some examples of gear that can still be useful at higher levels. I’ll start with one example: the ooze beater.
There aren’t many readily available everbright or glass weapons beyond Muckbane and Muck’s Doom. With Cannith crafting you can make a blunt everbright weapon with some nice options for prefixes. The everbright suffix also means the weapon doubles as a rust monster beater. The blunt requirement comes from trying not to split the oozes.
The first example is a Screaming of Everbright maul. Sonic damage is nice and generic as few mobs have resistance against it, nor does it put any requirements on the wielder. With a minimum level of 12 with masterful craftmanship, this weapon has a remarkably long lifespan.
If your character is chaotic or has a UMD score of 20, you can use True Chaos instead of Screaming. True Chaos inflicts 1D6 damage against neutral mobs such as oozes and rust monsters, with the added benefit of breaking DR/chaotic. For bonus points find yourself an adamantine blunt for a blank to make it a Marut and clay golem beater if you don’t want to carry a blunt or chaotic smiter.