Using the arsenal of a ninja takes years of dedication and constant practice. Just try using a throwing star and having it actually hit the target properly. Grab a set of nunchaku and try to wield them without seriously hurting yourself. Find a martial arts master and see if you can land a punch on her. If this is your first time with each of these situations, it likely won't be pretty. A ninja dedicates his or her life to learning and practicing these skills. He continually trains to hone them, and because of this dedication and hard work will become a deadly and effective master of these arts. Without such training, the weapons are just so much dead weight in her hands.
In the same way we can only be masters of the Biblical arts by constant training. We need to go to the Bible every day, pray, and listen to God. Reading the Bible, learning the Scriptures, and studying under our daimyo (Jesus) are the only ways that we can be effective spiritual warriors. If we just go through our days and don't train in the Word, it will be worse than the average person picking up the nunchaku and hitting themselves in the head or groin. We need to train our skills and spiritual reflexes to be finely honed so that we are ready whenever we have to face our Adversary. God gives us the tools for training, but we need to actually use them.
He trains my hands for battle; my arms can bend a bow of bronze.