But for real, I don't understand any of this jibber-jabber about Carnifexes and adrenaline and sentient weapons. The only things I understood were "at low lvl you want crit chance, at higher lvl you want more crit multiplier" and "maximize the product of the total range and multiplier"
Carnifex has a 17-20/x3
critical threat range; basically meaning that on 20% of your attacks, you'll do triple damage. For a level 4 2H weapon, that's pretty great, especially since many class-based crit threat bonuses don't become available until level 12. So at low levels, about the only times you wouldn't want to use Carnifex is you're fighting something with
Fortification (thus negating Carnifex's best feature) and/or
damage reduction that resists slashing weapons (e.g., skeletons).
As the wiki page shows, almost every class gets some sort of critical threat bonus. So figuring out what's the best weapon for your build depends on which bonuses you plan to use, since you want to increase both the frequency and magnitude of your critical hits as much as possible. E.g., a 2H barbarian with Frenzied Berserker's Focused Wrath (+2 crit multiplier) will want to use a weapon with a wide crit range such as falchions: 18-20/x2 base -> 15-20/x4 with Focused Wrath + Improved Critical feat, meaning a 30% chance to do
*Quake announcer voice* quad damage. OTOH a 2H barbarian who takes Ravager's Critical Rage (+2 crit range) will want a weapon with an already-high crit multiplier like Riftmaker.
Okay now we get a little more advanced. Adrenaline is an Epic Strike in the
Fury of the Wild Epic Destiny: "Your next melee attack deals +25/50/75% damage, and increases your threat (range) by 4/8/16." Because of that big boost to threat range, you are almost guaranteed to crit with an Adrenalized attack (presuming you hit, of course), regardless of what your weapon's base threat range is. So the bigger your crit multiplier, the more damage you'll get from using Adrenaline. Hence my comment, "Adrenaline favors weapons with higher crit multipliers."
Even better, if you pair Adrenaline with a special attack, the +75% damage bonus will stack with whatever damage bonuses that special attack adds. One example is a paladin using Exalted Smite: "An improved Smite that adds [+1/+1/+2] to your weapon's critical damage multiplier and [+0/+1/+2] to your weapon's critical threat range. "
Frankly, this is just scratching the surface of DDO's DPS math, but you gotta start somewhere.