In an UNPATCHED game, it is possible to switch the Assassin's Dagger from one character to another while they are becoming an assassin and thus keep the nice dagger. It is also possible to hack the dagger as well.
Treasure tends to be random in this game. In more difficult areas you tend to get better treasure, but there are only a few places where the treasure from a chest is pretty much the same from one player's game to another. You can always try saving your game before opening a chest to see if you like the treasure. If not, reload the game. Over all, I don't think it is really worth the time to do that but it is an option. If I recall correctly, Saz didn't find a Wizard's Dagger until his 4th game.
Wyv