Okay, I get the desire to collect trait raising tomes from certain rumor bosses, but the reality is that you're not going to get one. Someone might. A few claim to have, but really, it's like winning the lottery.
Only the toughest rumor bosses drop them (dragons, lich) and the drop chance is less than 1%. While the chance to get a tome to drop is 1%, the tome is at the bottom of the loot table with a chance of getting max loot items before even rolling for the tome. If you reach your max loot items, you don't roll for anymore items. This all happens in the background.
And before you ask, saving and re-loading to try to get a better drop is considered an exploit and discussing exploits is prohibited on the forum by the forum rules. Also, the game was updated some time ago to lock drops to prevent that very feature.
Also keep in mind that each tome only gives 1 trait point. It takes an increasing amount of trait points to raise an trait, so even getting an dropped tome won't impact your game too much. It might help if you're one point away from increasing a trait, but other than that, you might just have a trait point with no way to spend it.