Hammer is a trading item in 80 Days.
It likely is usable by Passepartout as a weapon, as Fogg speaks of Passepartout's possession thereof as being "well-armed". It may also be used as a weapon by the assailant during the incident on the Noelani. It will be confiscated upon arrival in Moscow from St Petersburg, though whether the basis for such confiscation is its use in Artificing or its use as a weapon is not specified.
Warning: it sometimes breaks delicate items in the same suitcase with it... Not always.