It’s the second error I found in the whole book, so I’m positively surpirsed by the good work of the editors.

Karttikeya is the first lifepath of the Vaishyen Caste (p. 186). And it is the 6th LP of the Ksatriyen Caste (p. 184).

But perhaps it is no error but deliberate?

Actually, a number of lifepaths do this – Coeptir is both Nobility and Hammer, Lord-Pilot Anvil is both Nobility and Court. It can be a little confusing, and it’d be ideal if the book always changed the name to clarify the setting (e.g. there’s Coeptir and Court Coeptir, so why not Hammer Coeptir too?).

But all that’s happening is that there are very similar, but not identical, versions of the lifepath in different settings. So both versions of Karttikeya are armorer and weapons technology specialists, but each is approached from different prior lifepaths and has a slightly different skillset.

Right. My mistake.

Thank you for taking the time explaining it to me.

Your mistake? No, just perfectly reasonable confusion.