One of my contacts who picked up the Forgotten Realms Campaign Guide informed me of the following new magic weapon:
Goblin Totem (Level 2+)
Level 2 - +1 - 520 gp
Level 7 - +2 - 2,600 gp
Level 12 - +3 - 13,000 gp
Level 17 - +4 - 65,000 gp
Level 22 - +5 - 325,000 gp
Level 27 - +6 - 1,625,000 gp
Weapon: Any
Enhancement: Attack rolls and damage rolls
Critical: +1d6 damage per plus
Property: Your attacks with this weapon against a creature of a larger size category than you have an additional bonus to damage rolls equal to the weapon's enhancement bonus.
So... yeah, you'll be fighting Large-sized creatures quite often, so this is passive extra damage you'll be getting on a regular basis. And if you're a Small-sized creature, like a halfling or a kobold? Even better, because then you'll get the extra damage even against Medium-sized creatures.
Sweet, Small Rangers will love this... hmmm, let's see... Halflings, Goblins, and Kobolds. Let's try:
16 Kobold Ranger/Stormwarden, +4 'Goblin Totem' Scimitar w/Scimitar Dance, Weapon Focus, Power Attack, TWF, and Lethal Hunter, and assuming attacking Medium or larger opponent (likely anyway).
16 Str +3 stats +1 tier = 20
12 Con +2 racial +1 tier = 15
16 Dex +2 racial +3 stats +1 tier = 22
12 Wis +1 tier = 13
DPR PAing = .4*2*(1d8+4*2+2+4)+2*0.05*(3.5+4d6+2d8)+0.4*1+(1-.6*.6)*2d8+.6*2(6)+3*6 = 14.8+2.65+0.4+5.76+7.2+18 = 48.81
Not PAing = .5*2*(1d8+4*2+2+4)+2*0.05*(3.5+4d6+2d8)+0.5*1+(1-.5*.5)*2d8+.5*2(6)+3*6 = 14.5+2.65+0.5+6.75+6.0+18 = 48.40
Not PAing on second attack if first attack missed (should be off-hand first, so the TWF damage is more likely to not be PA'd on)
= .4*(.4*2*(1d8+4*2+2+4)+.4*1+.6*2(6))+.6*(.4*(1d8+4*2+2+4)+.6*6+.5*(1d8+4*2+2+1)+.5*6) +2*0.05*(3.5+4d6+2d8)+(1-.6*.5)*2d8+3*6 = .4(14.8+0.4+7.2)+.6(7.4+3.6+7.75+3)+1.75+6.3+18 = 8.96+12.75+2.65+6.3+18 = 48.96
PAing with a Vicious weapon: 11.6+3.25+0.4+5.76+7.2+18 = 46.31 = -2.6 DPR = -1.3 DPR per attack.
In Epic, the difference between them will be (0.1(6d6)+0.5*6) - (0.1(6d12)) = (2.1+3) - (3.9) = 1.2 in favor of Goblin Totem. Clearly, before the crit chance gets better, it's also in favor of Goblin Totem. This is ignoring things like Prophecy of Doom, though.