At 15 quests in and 45 lock boxes later, I find myself with the almighty and glorious Dagger motif pages. With this success rate of 0.06% repeating and 13 more pages to go, I can say I'm really looking forward to getting acquainted to merchants who put way too much money in putting portable chamber pots in safes. Oh well, I only have to break into another 585 lock boxes, assuming I don't get any repeat pages. Maybe I can pick pocket 1,950 people instead...

Update: Make it 780 lock boxes, or 2,600 pockets to pick, assuming no pages repeat.