Dargon 378. Small warrior's defense should probably by a shield or feat bonus. As is it stacks with battle clerics lore and bunch of other stuff. Its not a huge issue by itself that it is untyped, but halflings in particular can get super high AC with it. It stacks with the untyped bonuses from lost in the crowd, the tactical warpriest bonus, adamantine soldier bonus, the shield bonus from battle clerics lore, and feat bonus like scale specialization. That leaves out power bonuses.
I have a halfling build that gets the equivalent of scale +7 at level 16 (+11 when bloodied and next to 2 medium or larger creatures) and it goes up to scale +8 (+12) at level 21.