I'm thinking the stance will unlock 2 weapon skills, one after full thrust and one after chaos thrust. Since chaos thrust combo is more debuff oriented and FT combo is more direct damage, likely the 4th finishers will follow in suit. "Fuller thrust" might be 420ish potency or something, and finsher after Chaotic Thrust could be like STR-10% on the mob, or reduce the mob's critical hit evasion by 5%(indirectly increasing the raid's crit hit damage by 5%).

Then we might have an oGCD that expends the stance but delivers big damage instantly, say 300 or something.