Try the Bigsandwich build. Polearm, get a few points in shield (I'm using 2 just fine currently), but stack agi even higher than 24 to offset the shield weight (15/27, 18/27 at highest levels).
You don't need to use the shield in fights, but getting to fights at full health is nice. You'll zoom around the battlefield getting strong pierce damage and support hits. Polearm hits stop enemies for a brief moment, allowing you to circle around them with a teammate on the other side. 8ath also works, but the shield would make you move only slightly better than a 7ath no shield build.