From what I understand pure iron is too soft and very hard to isolate even today, cast iron is is too brittle to make tools or weapons and carbon steel is relatively late invention. So what is the iron that were used before that?
Iron used in antiquity was neither pure iron, nor was it cast iron. It was an alloy consisting of iron, a negligible amount of carbon, and thin, wavy slices of silicon.
It's commonly called "wrought iron", meaning it was been worked, as opposed to cast iron which is poured.
Steel was still around before the Bessemer process, but was expensive and not quite scientific enough to produce a consistent product.