Each dragonslayer weapon captures the memories and personality of the first dragon it slays. You tap those memories for your own use.
Memory of the Dragon is a 12th-level ritual.[Dr385:29]
When you complete the ritual, you ask a question of the first dragon slain by the dragonslayer weapon you hold, and it answers that question to the best of its ability. It knows only what it knew in life and has no particular foreknowledge of events (though it might speculate).
If you choose, you can instead view one of the dragon’s memories as though it were happening to you. You can name aspects of the memory you want to view, and if you make no restrictions, the ritual shows you a memory pivotal to the dragon’s experience.
This ritual can be performed only once every 24 hours.