Anyone knows exactly which weapons can be obtained with lucky coins?

[Hrith]

Because you use a Shot, which was too slow to make the bonus 13 levels worth it.

Shots aren't slow, and it's the best weapon type to put Jellen or Zalure on, since it covers the most area. And I'm talking about damage difference, which isn't noticeable.

In case you had not noticed, this thread got off topic when Kefka said the 9-star shots were "very good weapons" after I did not include them in a list of "notable" weapons you can get, though I did mention the shots in my post. IMO, they are just not good, and they are easily outperformed...

Definitely not by Needle, or Rifles, Handguns, Bazookas, Mechguns...

Now Kefka is saying that Slicers are by far the best in the game.

Always have. I'm talking about the weapon type, not a specific slicer.

Kef's whole point is that, when you're in a team, slicers would outdamage needles because the enemies would rarely be grouped closely enough together to make the reverse possible. Think CCA (regular CCA... not towers, in which a needle is virtually useless anyway); play in a team of four and I'll laugh if you try to follow around all the Gibbons to line up a needle combo. Granted, Gibbons might be a bad example because they even cause rangers ATA trouble occasionally (at least on things like slicers)

Hmm, no? Slicers are more accurate than shots or needles, and it's definitely the best weapon type to use in GDV. I never use a shot or needle in GDV, always a Slicer.
I hope you know weapon types have inherent accuracy, if you haven't realized that at your levels...