If you can afford to upgrade the photons at least, RoL/Hope is a good one to start with. Also while pulverizer would have probably been a better choice, I wouldn't say owl's eye was THAT bad since it does at least provide some good CC and could be used in a flying weapon deck since you have a few of them now. You might also consider trying bronze league arena and see if you can win some more rares from there. As for selling cards, I'd say don't sell anything until you have at least 12 copies(or more than 6 upped) of it since you lose money every time you sell something and then have to buy it back later. Anyway, you're probably at about the hardest part of the game right now..it gets much better once you have a decent FG grinding deck and can start winning upped cards and earning money for new decks faster.