nocumento is 'harm', rather than 'harmful', so I would go for a noun rather than an adjective. Hurt, harm and injury are all words with centuries-old pedigrees. Mischief could also be used in this sense, but perhaps sounds a little too medieval. The only reason I might choose 'hurt' rather than any of the others is that it is now used mainly as a verb, and much less as a noun (especially in the sense of physical injury), so its use here as one could give the slightly antiquated flavour which is what you seem to be after. The complete phrase could be 'caused no hurt', for example