I'm building a Ranger(Scout) for an upcoming campaign and I was wondering if, while using gauntlet-axe, I would be able to Make two handed attacks using versatile weapons (such as the bastard sword)? In the builder it won't let me, but it also doesn't let you slot the gauntlet-axe into the arms slot which the compendium explicitly says you an do. It has shield like qualities, but doesn't actually fall into the shield weapon group. I also am assuming that it functions like wrist razors and spiked knuckles. I'd appreciate the folks here to weigh-in before I talk to my DM about it. For the purposes of this question I am talking about a mundane gauntlet-axe without an enchantment.
Because it leaves your hand open you should go ahead and put it in your weapon slot anyways. You're going to want it enchanted as a weapon and not a shield anyways so you want it there.
Second, just because it's in your hands slot, does not mean it's consuming that slot. It's on your hand, but the text obviously allows you to wield your bastard sword two handed.
Finally, you can definitely use the scout power Dual Strike with your bastard sword two handed. You will get the damage bonus and also be able to attack with the gauntlet axe.
Important: If your DM for some reason does not allow you to attack with the gauntlet axe while using the bastard sword two handed, take your hand off the sword for the second attack. Changing the number of hands a weapon is using is a free action thus you should be able to easily take your hand off the sword, strike with the gauntlet and grip the sword again. (This should be unnecessary as the text is pretty clear here). If your DM still does not allow this, just move on and try a different strategy.