Be "holier than thou". Since Will never plays, you're the team conscience. Your good. Penultimate good. When we capture a guy, you should be the guy who says we turn him over to the local constable. When the thief knifes a dude in the back, you should be the one to reprimand him for doing things unhonorably. If you have trouble with this, there's a series of books called the Dragonlance Chronicles with a character called Sturm Brightblade, who is has exactly the type of attitude I'm talking about.
First off, buy better armor on next town pull. You might be at a, what, 5 AC right now? But guess what, you ARE THE TANK. DPR is second to AC/HP strength. You can kill guys too, but make sure you're absorbing damage so that the squishy members of the party (i.e., everyone else) doesn't get ganked. I'd suggest Plate, but at 400 gp it's a bit steep. If you don't want to spend that much (you'll be downed quite a bit after your tithe anyway), I'd suggest Splint Mail. At 80 gp, it's fairly cheap, 10 gp cheaper than Banded Mail which gives you the same AC. With a shield, it will drop your AC to 3.
Next, let's look at weapon choice. The bastard sword you currently use has no plus to it, and we don't seem to be fighting many large size creatures, so that 2d8 against larges is useless. With an average DPR of about 5, it's not exactly brutal against medium or small creatures. It does, however, keep you from doing only 1 point with it's 2d4 mechanic. However, in the last combat we picked up a +1 Longsword. With mediums and smalls, it does a 1d8, so a DPR of about 4. 1d12 against larges, but that really doesn't matter. What's important it that it not only will hit more often, it also will allow you to pick up a Large Shield at the next town, getting you another point of all-important AC. Plus, a Large Shield only costs 15 gp, bringing you at the same level as Plate Mail without a shield for 95 gp, if you use the suggestion above.