Vamos gains the ability to ascend weapons down the Chaos path after receiving the Chaos Flame Ember. Creation of a Chaos weapon requires a +5 Fire weapon (which in turn requires a standard weapon +5), Red Titanite Chunks for upgrading to +4 and a Red Titanite Slab for upgrading to +5, as well as the requisite souls.
The Chaos path adds Fire Damage to a weapon, but removes all stat scaling bonuses. This makes it a good choice for lower levels. However, Chaos cannot be augmented. This, along with the lack of stat scaling, ultimately means that Chaos weapons have an inferior damage potential in the long run.
Uniquely for weapon upgrade paths, the Chaos path scales with humanity (up to 10). At 10 humanity, Chaos weapons are superior to Fire weapons (and, indeed, nearly all the other weapon paths in terms of raw damage) that are upgraded to the same level. However, they are inferior if the player is lacking in liquid humanity.
Compared with Lightning weapons, Chaos weapons with optimal humanity deal more damage against unprotected foes; however, as most enemies possess more Flame than Lightning Defense, Lightning weapons are often a better choice.