A plethora? Only if you switch covenants. Prior to the recent hot fix the only thing to continually spend Anima on was healing your companions at the mission table or doing a vendor shuffle. If you already have the rank 3 achievements you swim in Anima without really trying. If you do all the world quests for Anima then you'll be filling up your bank with stuff you can't deposit.
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You don't need the highest rank legendary to test them out. The proc/effect is the same across all ranks and the only difference is the stats that are on the item. So just buy a cheap rank 1 (or 4) and wait for prices to drop on ranks 5 and 6. The cost is the same and soul ash is easy to come by including being able to farm it repeatedly (though at a reduced rate the then first layer clear of the week). You can also go straight to rank 4, 5, or 6 if you want. The cost automatically adjusts.
Covenants are like a class choice. If you want to change that progress doesn't carry over. You lose that progress otherwise people would be switching at will to min/max in the moment. It really isn't that big of a deal to have to re-earn that stuff though over the course of the expansion. And you'll be swimming in Anima so the costs are not that big of a deal if you just play the game.
Conduit energy exists to limit min/max swapping for each encounter. It really isn't that big of a deal though as there isn't that big of a reason to be constantly switching them out. Balance and sims don't change that much that you really need to encounter it.