I don't think we're going to get weapon balance. Regardless, many of the weapons you listed are very balanced.

Fire weapons in particular are fine in their balance, but fire as a status against monsters is rather weak when one shotting everything is a reality. To solve this we would want-

1.) Fire to receive a slight buff in its damage against monsters, as it currently doesn't do enough

2.) More areas with enemies with low health like slime minis, glop drops, etc.. These make fire a viable crowd control option.

3.) Enemies with multiple segments would multiply the effects of fire. These are what SK needs most, as they would assist bombs etc.

But on we go to plague needle. This weapon is probably stronger than blitz, save for two factors-

1.) Poison needs to last longer to accomplish its effect, similar to curse

2.) We need some form of enemy that heals at an absolutely ridiculous rate, making blitz needle a lesser choice. Said healer should be incredibly painful to heal, and should come back akin to a phantom. I would only suggest putting such an enemy in "dangerous" areas, like danger missions and shadow FSC.

Owlite wand in particular is very balanced. They actually did a good job with that one, as did they with dark retribution. Dark retribution is the power level bombs should all be at.