Sorry for not having answered earlier, Troth, many thanks for your comments, support and advices. I like your distinction between fluff and crush. Personally, I'm more interested in "fluff" stuff when I read a sourcebook, but you're right, many readers can be in need of "crush" stuff, because they will reuse it in other contexts, areas or eras. In that way the Silver Bow and even more the Narbul bombs are good examples. The former are the best bows to be found in Magnamund, while the latter are exclusively produced by the Cenerese, which can virtually be found -and faced- everywhere in Northern Magnamund.
Sorry for the stats of the Narbul Bombs: they should be found in the Assassin Class which has been removed (some assassins of the Stornlands, namely the Assassins Guild of Duadon, have strong links with the Cenerese). I hope we'll manage to publish it soon.
Thanks also for pointing the fluff or crush based purpose of a sourcebook. Indeed, Darklands and Sommerlund are quite different books, the latter providing few (relatively) information about the defenses of the Kingdom of Ulnar. In the future, it may be useful to add such data in scenarios made for teams of Drakkarim PC, or even in the sourcebook itself (for example data about obvious targets of the Drakkarim, like the weak points and strength of some forts of Sommerlund, like Shadow Pass or Fort Durnspa, or Lencia, like Maycastle).