A good bo shuriken is easy to make.
Use 6mm or 1/4" square bar stock.
Cut into 15 cm/6" lengths.
Sharpen one end in square facets (not rounded) about 25 mm back from the point.
That will give you a basic Meifu Shinkage Ryu blade which is a good, all-around bo shuriken. I brought a bunch back from Japan and they are nice, but you can make your own for a tiny fraction of the price.
Shuriken are not knives: they don't need to be heat treated or polished.
Do be sure to check the weight and match them all as cloesly as possible.
Throwing shuriken of different weight and dimensions is bad.