The redeye ring is a must as it is what allows the tank to hold aggro. Two handing a great-shield lets the tank do the job of tank most effectively. The goal for this build is to hold the focus of enemy attacks while other players are able to dps without much worry of getting turned on. I don't recommend that stats get put into Adaptability as the great-shield tank will hopefully be blocking attacks instead of rolling, and with the weight of great-shields already being quite a bit the points would be better spent into Endurance, Vigor, or Vitality in that order. This build is more of a skeleton build and allows for the rest of the build to be change as required by the zone or play-style.
Weapon: Havel's Great-shield - Two handed this shield can take hits from most bosses with very low stamina drain while still being able to hit decent when the opportunity comes up.
Rings: Redeye ring will make enemies focus you without having to deal lots of damage… or much other than stand there. The elemental resistances rings would also be beneficial to reduce damage from elemental sources not 100% reduced by the shield.
Again this build is for co-op and is only a skeleton of a build.