To use the term deadly is actually a tradition of men, nevertheless sins are indeed deadly, and ought to be heeded by every professing Christian. But if we must have a title for Proverbs 6:16-19, it seems it would be “The Seven Hateful and Abominable Sins”, and we could add four more also, and they are: “And let none of you imagine evil in your hearts against his neighbor; and love no false oath: for all these are the things that I hate, saith the Lord”, and also, “For the Lord God, the God of Israel, saith that He hateth putting away…”; and again, “Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God”.
But if there were a sin which could have been referred to as deadly, it would have been the blasphemy against the Holy Ghost.
Nevertheless, glory to God that you have listed these seven sins, for we who profess Christ need to know as much as we can about what sin is according to God, rather than what we think is sin, and moreover what we may not think is sin, may very well be sin according to God: we need to know them to be able to recognize them.
It is like that man called Simon in Acts.8:18-24, who, although he believed and was baptized, did not know that he was yet living in sin, until Peter informed him; for without the knowledge of God or the mind of God, we can only assume we know, but then our sins are left untouched, if we really don´t know.
It is a good thing to list what are sins according to God, if we have not the knowledge of them in our heart.
The grace of our Lord Jesus Christ be with you.