Verse 5 says "Yea, and for this very cause adding on your part all diligence, in your faith supply virtue; and in your virtue knowledge- To defend the Gospel, one must know what the scriptures teach. Once a Christian begins to grow he can move on to the "meatier" things contained in the Bible.
Another benefit of proper hermeneutics in a Bible study is unity. As God's children, we are commanded to be united. If we can understand the scriptures alike, then we will be united. In 1 Corinthians 1:10 the Scriptures tell us "Now I beseech you, brethren, through the name of our Lord Jesus Christ, that ye all speak the same thing and that there be no divisions among you; but that ye be perfected together in the same mind and in the same judgment." United Christians mean a united church, which means a church that will withstand false doctrine and those who teach false doctrine.
If proper hermeneutics is used and the Church is united, then another benefit is the healing of division. If Christians get more of their "spiritual food" through Bible study then proper hermeneutics could bring all Christians to a common interpretation of the Bible, then the power to create divisions would be gone. Some divisions occur because some have been taught a particular view from childhood, and all their studies in the Scripture have been to sustain their belief. Sometimes traditions of man become absolute and assume an authority all their own. They even take a life of their own leaving the Scriptures behind. When this happens the Bible is used in the support and defense of these traditions, thus the scriptures become the "means" and the traditions become the "end." We must remember that if the Bible is God's book, it can be understood by everyone through the use of proper hermeneutics in a Bible Study.
Understanding how God wants us to serve him, both during our worship service and our daily lives, is another benefit for the proper use of hermeneutics in a Bible study.