A 59-year old New Fairfield man is being held on $750,000 bail for allegedly fatally stabbing a man at his home over the weekend.  Bail was lowered yesterday for Patrick Griffin during arraignment.  The judge said there may be evidence of self-defense, and while he does have prior convictions, none are recent.  Griffin was charged with manslaughter for the death of  65-year-old James Knapp of Sandy Hook.  Defense attorney Thomas Leaf says intoxication might have played a role in a violent struggle. Griffin and Knapp were transported to the hospital for treatment of injuries, and Knapp was pronounced dead at the hospital.