Yes the vampire fang is not strong enough I would recommend changing it to Agi since it is used in the life stealer which is an agility weapon.
Currently the combat kings vendors are only selling like 8 items none of the ones that cost 3 boss points each. (thats what I call tier 3)(for example the vendor does not offer to sell the berserk combat kings book)
The crashing on chapter 4 only occurred for me when I started from the prologue and worked my way to chapter 4 again. Updating my game version sounds like it will fix this issue.
Oh, and small thing but it would be nice if a person could pick up a ring of agility in chapter 6.
Thanks again for the most epic campaign ever! I eagerly await the next chapter in a month or 2