Does that augmented weapon give you the same or more skill levels than what you are comparing to? Does it give more accuracy? If no to either of those, it is worse. Skill levels count for damage and accuracy against higher level enemies, and when taking on the hardest content you need really high accuracy to even hit an enemy. What good is OAT if you have a 50% hit rate, so one of the extra hits misses? Level 119 weapons are that level for a reason, they give you stats like you are level 119 instead of 109.
Now, if just wanting to do missions, even sparks armor and weapons are enough to solo through Wings of the Goddess and Voidwatch (most of it). Some of Adoulin is not soloable unless you are the right job with the right gear and Job Points/Gifts.