Using regular School glue is absolutely fine to use. Hot glue burns you sometimes, and superglue dries too fast.
You are not supposed to make a thick stream of glue, but rather use the tip of the bottle to distribute a small drop of glue on the tab, then glue the pieces together, holding the Tab in place while you press really hard. This will make the glue sort of seep into both sides and cure really well. Less glue = Less hardening time, less warping and less mess. School glue is the way to go, IMHO.
As for hardening the weapon itself, if you were to somehow get a hold of some Smoothcast 300, you could pour it in there, stir it around and let the first layer cure. Repeat as many times as you feel necessary. Otherwise, you can also pour resin into the model, let it flow around into all corners and wait for it to cure, just like the hot glue method.
Hope this helps you.
Keep it clean!