As the title says do those keywkords stack? I know that the rules say that defense doesnt stack u just use the best source but what if a character is weilding to weapons with the defensive keyword? Do they both increase there defense or do they just use the best one?

Check the Errata, defenses and how they stack is fully explained there, with updates.

Defensive and Deflection are labled as Increasing Defense rather than granting Defense, so yes, they do stack. If you are asking about dual-wielding, I don't know if there has been a ruling on that. However, I as a GM would rule that they do not stack, as, for example, Accurate on the off-hand weapon does not stack. I'd say that only Defensive/Deflection from the weapon in your primary hand actually counts towards your Defense.