Carbon 14 dating is reliable for rocks that are
The sword smiths combine a higher carbon steel for the cutting edge and a lower carbon for the core of the weapon, thereby making an extremely sharp yet extremely durable sword.
Heat is also a main factor in the construction of a sword, by heating the blade to high temperatures and quenching it at different rates you can achieve many variations of hardness in the steel.
The new isotope is called "radiocarbon" because it is radioactive, though it is not dangerous.And yet we know that "radiocarbon is forming 28-37% faster than it is decaying," which means it hasn't yet reached equilibrium, which means the ratio is higher today than it was in the unobservable past.We also know that the ratio decreased during the industrial revolution due to the dramatic increase of CO produced by factories.During the 19th century, and even well into the twentieth, geological chronology was very crude.Dates were estimated according to the supposed rate of deposition of rocks, and figures of several hundred million years were bandied out; usually arrived at through inspired guesswork rather than anything else.
So, if we find the remains of a dead creature whose C-12 to C-14 ratio is half of what it's supposed to be (that is, one C-14 atom for every two trillion C-12 atoms instead of one in every trillion) we can assume the creature has been dead for about 5,730 years (since half of the radiocarbon is missing, it takes about 5,730 years for half of it to decay back into nitrogen).