I think the most easy way to fix the class would be to let dwarven-defender levels meld with fighter levels as one of the alternatives in this suggestion brings forth and i do think Dwarven Defender could afford some minor buff to AC and AB to be on par with other martial-classes. The barbarian stand as a class that right now is for most part just a plain better at everything the Dwarven Defender can do. The 10% more soak and hp shield make sure that they are very much on-par when it come to soaking and makes barbarians better to take dmg from WM's and crits. Especially half-orc barbarians.
To me this is the most interesting role-play enhancing idea yet that i have seen for the class would be to let DwD increase the efficiency of each other, other dwarves, or other in a party through knowledge of tactics and how to act in a unit. In some way the opposite of a barbarians approach of chaotic-individual rage. It fit the dwarven approach of Warfare. Small unit-tactics. Their mindset with focus on the collective rather then the individual. I like this one, because it's not just a plain mechanical buff or fix but give something more in way of feel and soul to the class and can help illustrate the highly disciplined training and tactical acumen of the Dwarven Defender.2. Dwarven defenders have undergone rigorous training. To deploy their most refined techniques, the Dwarven defenders require coordination with other Dwarven defenders on the field of battle.
For every friendly Dwarven defender within 20 feet (or 6 metres), the Dwarven defender is granted +AB, damage and reflex up to the maximum of 2 bonus.
Design note: This is a blatant buff, but it encourages the Dwarven defenders to seek each other and act together, hopefully leading to more Dwarven defender RP. The bonuses are capped for obvious reasons. The buff is given to AB and damage, because these are the departments Dwarven defenders currently lack in; however, even this is limited to only 2. It makes the class a worthwhile investment for other builds, such as Dwarven defender Rogues, Clerics, and so on. This broadens the DwD build palette from that of a simple damage reduction build, which I think is something the players tend to enjoy.