[kronckew]

you'll need a very large diameter pipe for a curved shamshir, or depending of the curvature you might get away with smaller diameter if you heat and bend the plastic pipe to fit. one with a healthy parabolic curve would require an interesting bend. you might need to slit the top, like they do with scabbards, to accomodate the last part of the blade, then seal the slit with a good water tight tape. if the curve is a circular arc segment, a simple bendy capped pipe will suffice. the smaller diameter the better, as it will take less liquid to fill it. for a simple curve, you could even flatten it after bending and thus an even smaller diameter pipe would work. i'll leave it to you to figure out what dia. you'd need.