Go ahead and use them as is. When they get dull---which will be fairly quick---take your time and sharpen.

Using a slow speed grinder or sharpening machine will help prevent overheating. There are many machines designed to sharpen lathe tools on the market.

Another tip is to have a small bowl/jar of water close. Grind and dip type procedure.

Once you get the darkened area removed, don't wait for the tool to dull before sharpening. Whet stones work well to sweeten an edge, for instance.

Thw sttel is just softened, and wil not hold an edge as long after sharpening.

if you are just geting started use it as a chance to practie sharpening more often.

It is posible to re-harden and tem temperthe tools (approximately since you are lulikely to find therexact type of steel used).

It is simple in concept though.

Heat to red heat, quench in water-oil-brine (depends on type of steel).

One relatively constant thing is heating till the steel is no longer attracted to a magnet, then quench.

Re-heat 9not as hot this time) and allow to cool slowly to temper (soften) or the steel will be so brittle is will crack easily.

Unless the burning went deep, you will slowly sharpen back to better (harder steel).