Hello!
Bronze arena is pretty easy to farm with all the 1 hp decks, so this is a good way to do it. If you want to just farm as fast as possible, I'd suggest using a deck with as many zero-cost creatures as possible to get fast EM wins on 1 hp decks. Of course, that gets boring real quick, so it's perfectly fine to continue playing with a "real" deck.
You don't actually need too many shards to get a good FG or plat grinder. Pdials and Swallow are the two most common ones, I think, and you only need 3 of Shard of Divinity for the former, and 3 of Shard of Patience for the latter. They do work best fully upped, though.
We'd love to see you in PVP events - feel free to join us in chat whenever you're around.