actually, you can get them from any wyrm/wyvern/drake. its a rare drop (guide: 1% when wings destroyed) ... i got 5 wyrm tears, 4 drake tears. killed 23 drakes and 10 wyrms so far. wyvern only 3, so there will be one in the future i guess.
the guide says about the tears, that monster drop different things, when a tear is in your inventory. but all that is different: wakestone drops. nearly every boss monster drops wakestones with a 30-100% chance, depends on the boss...
chests will not be affected by the tears (description says also change drops in the everfall). i think changing vocation affects more than that. i switched to ranger and the first chamber i went in gave me all rare equipment i haven't looted to this point...