I have cleared both these islands numerous times. A Tegi has never spawned. I know others who have cleared these islands multiple times and a Tegi has never spawned. I suspect the actual location for a Tegi spawn is the "secret" area through the tunnel. It's a lot harder, compared to these islands. So if you're thinking this is an easy camp, it probably isn't.
The Cohort’s Flamberge drops off of the Tegi Cohort that spawns on the taller of the 2 islands where the Grol Baku and Vas Ren go-exist. These two islands are in the NW part of the zone across from the Elemental Island. You can either get your swimming skill up while swimming there or run the outer edge of the zone to get to it. The Tegi Cohort drops 2 items that I know of, Gray Leggings and the Cohort’s Flamberge, which is the more rare of the two.
Besides the Tegi Cohort there is a Tegi Leader and a Tegi Taskmaster that also spawns there. The leader drops a nice hammer and he taskmaster the Tegi Taskmaster whip.
There is a combination of 18 Vas Ren and Grol Baku on the island. I have not been able to determine if there is a specific spawn time or a placeholder. I have tried killing everything on the islands to see if it would spawn them. I have also checked the times. They just seem to be random. I have also noticed that some times the same named Tegi would spawn twice in a row then other times not. So it is really hard to say what causes them to spawn.
If there are any shaman Vas Ren or Grol Baku around when your fighting take them out first, they heal the others.
I was a 40th level Ranger when I obtained mine and most of them were green to me. There where a few light blue and the occasional dark blue. I think I went up 1 blue in 4 hours.
There is also a similar sword that drops off the Frenzied Shadow on Shadow Island, the Darkedged Two Hander.
So I hope this helps. There are some pretty nice items dropping in Twilight Sea but rarely anyone camping.
does any one know where this sword drops. I know how just where is the issue. I am guessing at the fire pits or around it after you swim throught the tunnel. which i have learned (the hard way) a paladin with 101 skill points in swiming and 88 sta can NOT make it all the way through with out enduring breath. thanks