You can receive a spell, you can’t use any stuff than has become a magic item. Your friend hits one of your possessions with a spell that makes it a magic item, you take it off because it is a magic item and you tell your friend not to do that again. <edit>
No, the greatsword with bless cast on it is a mundane object with a spell currently operating on it, and a holy avenger is a magic object.
I agree with the latter position- a mundane object targeted by non-permanent magic is not a magic object.
Indeed, since the ascetic's weapons are by definition not masterwork, they fail a neccessary prerequisite of being magic weapons.
A soulknife, on the other hand doesn't have a choice - and that is his only ability (well - essentially his only ability).
There was a question raised elsewhere about the interaction of the VoP and magical tattoos of a Tattooed Monk (or whatever the PrCl was called). The ruling was that the magical tattoos were a class feature and their use was not in conflict with the Vow.
I would rule similarly with the Soulknife. His blade is a class feature- indeed, it is the feature that defines the class.
As for the side issue of the spellbook, I also allow those. The only value of a spellbook is in the spells inscribed in it, presumably by the owner- straight off of the PHB equipment list, they are not truly valuable at all. Since the value is not inherent, but added by the ascetic, it is no more barred to him than if he took skills in a craft (say, Craft textiles) acquired some raw materials and a simple loom and created a well-made but simple robe for himself.
So by a strict reading of the VoP the following spells could never be used:
By the strictest reading of the VoP, there are a HOST of spells that could never be used because there are some who believe that since a divine focus is not part of a spell component pouch, it cannot be used by an ascetic.
I no longer have the thread bookmarked, but I once listed all of the spells that required the use of a divine focus- most of which are core spells for a holy person, and thus it is VERY counterintuitive to bar the holiest of the holy from casting. I'm talking about spells like Attoneme, Bless, Protection from {fill in the blank}...anything remotely resembling the duties of RW clergy.
Oh, and Turning...again, a counterintuitive power to bar from those most beloved of/dedicated to a divine force.