I'd rather option 5, a treasure battle doesn't occur unless the game lasts to turn x. X can be anything from 4 to 10, though I'd favor sooner then later, but the point would be that a player doesn't know if their match is even a treasure battle match until the game is well developed, then, if it turns out to be a treasure match things just get all the more exciting. This would allow them to alter the current system of how treasure battles are given out in folrart (currently the larger the winning streak, the higher the chance of a treasure battle occuring) since even if treasure battles we're given out evenly (but much more frequently) to all players regardless of win streak, a player could no longer abuse the system by just immediately quitting all matches until they get a treasure battle.
Though even more complicated to implement, an even better option still might be to make the turn on which a treasure battle is announced randomly generated as well, so a treasure battle could be announced on turn 4 one match, but not till turn 8 on another, in said manner a player couldn't just wait till turn x and then quit if no treasure battle occurred as she does not know what that turn x happens to be. Of course if a treasure battle was intended to generate it should still award the winner whether the announcement turn was reached or not to prevent players from just stalling out games in hopes of generating a treasure battle, but the system would still be far superior to just not letting players know they're in a treasure battle at all as knowing your in one, even if you don't find out till several turns in, still makes the match more exciting.
The overall effect would be there's less of a grueling incentive to repeatedly win (since you no longer need a big win streak to get frequent treasure battles) and less "the rich get richer" effect as well. Still, you still have to win the match to get the treasure so you do still want to be running a file that has a chance of winning, but anything that makes winning less important is a huge plus.
Anyway, my own suggestion aside, I don't think hiding the treasure reward is really necessary in folrart since the treasure battles come so infrequently, it was only because they were happening every game that they became an issue in crest. And while I'm not strongly against letting players "give" away their treasure reward, I don't strongly support that idea either as it both increases the likely hood of players begging, but also can severely decrease the fun and enjoyment for players. For example, I'm about to win a treasure battle with a lawtia card as a reward. My opponent is running a lawtia file and I'm not, but some day I might like to run one, or even if I don't, I could make use of the 5-30 gran in recycle value. I'm left with a no win situation, if I give it to my opponent like I probably would I feel bad for having thrown away a card or gran I rightfully earned, if I choose to keep it I feel like a jerk for not having given the card to some one who might have needed it more. Maybe a big spender doesn't care, 5-30 gran isn't a big deal to them, but for a free to mid spender, every gran is important. Winning a treasure battle should be a thing that makes you feel good, not a thing that makes you feel bad.
Anyway, thats just my long rambling thoughts.