Now they've changed the arena rank reward gems to an equal amount of Blended Seeds. I don't know anybody who would need more seeds, while the gems I've got I've used for frenzies or step chests. On my main I have like 3k seeds, why would I want more of them???
The armors you get from the Arena excluding the FBs have been useless for me for a long time. I guess I'll stop now at 16k reward to get the 20 gems...