What kind of dating method would you use on..?

Question

A wooden cross buried near some metal armour and sword blades?

Answer 1

Radiocarbon dating would be the best choice. Modern techniques don't require much material to be sampled but whatever is required will be destroyed during the test. The C14 test does not return an exact date but a range of possibilities with margins of error.

Since this in an archeological question you could also check the surrounding area and any other artifacts found 'in situ'. Also, a C14 test could be performed on any other organic material at the site. For example, if there is a nearby midden or fire pit those are excellent ways to date a site. They also provide charcoal and other organics that can be dated. If you have multiple samples to compare that increases the reliability of your result.

Answer 2

If the cross is large enough, dendrochronology may be an option.  Radiocarbon dating would also provide ± 40 year accuracy, but would require destruction of a portion of the cross.  The swords and armor can sometimes be used to deduce a nearly exact date if accurate historical records are available.