If you want to attach the sword to a certain vertex this instruction should do the job:
vec_for_vertex(sword.x,player,1234);
vec_set(sword.pan,player.pan);

If you have a certain offset (stored in the sword's skills) you could use this approach:
vec_set(temp.x,sword.offset_x);
vec_rotate(temp.x,player.pan);
vec_add(temp.x,player.x);
vec_set(sword.x,temp.x);
vec_set(sword.pan,player.pan);