Have you thought about using an epoxy resin? Unlike the glues, you can thin them with methylated spirit. The resin has all the adhesive properties of the glue, though it does take several hours to set.I tried that and it helped a little, but since the glue cools dwn quite fast upon contact with the handle, the effect was somewhat limited.
There is epoxy from BladeBond called HT that is supposed to have low viscosity, but it id not yet available in EU. Guys from english-handmade-knives.co.uk may introduce it (they already offer other types of BladeBond epoxy) after their own testing.
I was sanding the blade before the handle was mounted, so I could start the sanding motion higher up the tang. Once I have managed to get up to 400 grit and remove all previous scratches, I have used continuous strokes from tang towards the tip to get a consistent scratch pattern. I have used a 3x1x25 cm bar of wood and sanding paper with width of about 7-8 cm tightly rolled on the bar and I have made pulls with both hands towards me.Matus, how did you get the sanding lines so straight and consistent?