It seems you can craft Unity as many as you want so I'm going to replace my lowest item level slot each time.
The absolute best way is to use it on a RING.Because you'll gain HUGE stats, gem + enchant locked forever AND it won't take the place of any item since we can carry 2 rings.If you've got some important pieces except Tier pieces of course, you won't have to worry about with a legendary ring.
Honestly, just use the Belt. It doesn't conflict with any Tier slots, and the stat budget is fine.
This just seems like a convoluted mess at this point with the additional introduction of tier slots, its very off putting to more casual players. Really happy to hear that unity is account bound however, that's very welcome!
especially