Hard to differentiate between legitimate and faked lag. Unfortunately, Graal doesn't utilise distributed servers so everyone is talking to the same server regardless of distance/latency.
It could be considered harsh but one option is to have different categories of spars:
- < 100ms
- 100 - 250ms
- 250 - 500ms
- 500+ ms
It would allow you in based on your average latency in the last 5 minutes (The door should block you if you have only connected/reconnected in last 5 minutes).
It would be interesting to have geolocation-based sparring but Graal does not utilise such a service so hard to make accurate (and also the fact people will proxy anyways)