Ah. Didn't figure in Rage Spell. I almost never base any of my build stats off the assumption that I have a pocket bard/cleric/wiz for buffs. Anything above what I've got listed is a nice extra. Whether I up my STR or my CON, either way he could carry a Rage spell buff, and so it is a wash when discussing builds.
Bu, yeah, did forget to 1.5x the extra point of damage for 2-Handed weapons.
The 84-sec is -- +2 CON = +6 sec rage. Extended IV = 12 seconds. Times 7 rages = 84 seconds.
1-2 points of damage on a swing (depending on the 1.5 rounding up or down) and 4-5 points on a crit (Again, depending on rounding)
14 HP and 84 sec of rage
As for the +3 STR tome -- I don't generally make gear dependent builds. Yes - you can eke out an extra point of damage here and there once you get that tome. But you're doing the same amount of damage with less HP and rage until you do.
Once I hit level 16 and have another stat point, or once I pick up a +3 STR/CON tome, I'll probably take a look at moving some of the enhancements around to even those scores back out again.
If I can get hold of a +3 STR - I'll probably drop the Power Rage 4 for something else, although not sure it would be Hearty Rage. Possibly more Dwarven Axe Damage, or another of the Dwarf/Barb Toughness APs. With the new version of the toughness APs you can get 15 HP all the time versus 14 HP only when raged.
If I can get a +3 CON then I would probably either find a matching +6 CON item to go with it, or possibly use my level 16 attribute raise to even it back out again..