I almost think the RNG is slanted like this on purpose. For example, I was trying to get my WAR Ifrit axe right near when the game was released, I must have done it a dozen times a day for a little over three weeks before it finally dropped and I got it. Once I got it, i stopped doing it. With Tanks being in short supply and highly desired it would almost make sense to make their drop rate a little lower, forcing them to continue doing it beyond that of the plentiful DPS. It sucks but it would make sense. I would hope they havent designed it that way but I would understand why.