Stake weighting, not with network dispersity but with accumulated stakes. Sybil attacks are also not so easy and not even valuable for attackers to apply, and it is no big deal if it really happens.
Please at least read the answer I just replied, I don't want to explain the same stuff repeatedly.
The main idea of the paper was introduced here https://bitcointalk.org/index.php?topic=5094909.msg49129375#msg49129375.

First of all, thank you for your concern. But you don't have to be offensive because I am not your enemy but a guy who wants to share something and discuss them with someone interested. Maybe I have offended you with some unappropriate words that I didn't noticed, I appologize for that.  Anyway, all questions are welcome.