On the basis of objects that existed in RQ, yes. Easy example, the Sword Of Vengence in Cults of Terror can kill with no resurrection possible, for either slayer or slayee. This sounds like a Humakt the Avenger Secret, to me.
There is the matter of where the Secret came from. You might have to put points of YOUR knowledge in there, if you aren't using a bound daimon/spirit/essense to actually hold the power. Not a decision to be taken lightly.
> If so, must you know the secret (or be eligable to do so, even if you
> haven't actually got it yet) to use said item?
On the basis of objects that existed in RQ, yes. The sword above, from CoT, was a Humakti object that an Orlanthi used. OTOH, that sword was supposed to have a secret spirit that let only the "right" wielders use the Kill With No Resurrection power, which sounds like a bound daimon or wyter actually had and used the Secret, rather than just the dead metal. Its use was also an automatic initiation into Humakt and severed all other cult ties, so you might need to have equivalent geasa from the original cult.
> How heretical would it be to give such an item to an outsider ( a
> good friend from a friendly/allied cult)?
Heresy is bad belief, not bad actions, so it would not necessarily be heretical at all - I can recall a few cases where the gods gave things to non-worshippers, though usually of allied cults.
It might be a major sin, though, if not OK'ed by a prior divination. Even then, this sounds like a once-in-a-lifetime thing, not common practice. It might be easier to put the Secret into the object at the death of the original maker (who becomes like a small wyter), then require a member of the cult use the Secret for his out-of-cult master just as he might use his own knowledge of the Secret if it were higher than the object's.
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