Most of the time your hands move quicker than your head, that is when you usually die ^^. At first it is really difficult to plan ahead in case situations change, like status effects, etc.
Using a macro to switch weapons in SRO just doesn't work at all, I haven't tried but I never would either, just practice like the other guy said, with low level weapons, but in short, doing this won't really help, you need to be alert to changes in PvP, fighting an idle target is teaching you nothing, just switching belts