There's but one word that springs to mind when I think of the remaining artwork of The Arduin Adventure: gratuitious.
I mentioned earlier that The Arduin Adventure is 16 pages thicker than its' Holmesian equivalent. A great many of those additional 16 pages are devoted to illustrations and descriptions of various weapons, armor and magical items appearing in the Arduin setting.
Like Hargrave, I intend to be equally gratuitous, and show you some of the illustrations and accompanying text of those items.
Of course, it is not only within the pages of The Arduin Adventure that those items appear. Hargrave also published Arduinian treasure cards, like the two card sheets displayed below.
On the front side, illustrations of the items. On the back, descriptions of the items, along with space to customize the items to your game.
Several different sets of Arduinian treasure cards were published. I have several more sets, which accompanied the dungeon adventures published by Hargrave. If there is any interest, i'm happy to reproduce them here on my blog, for review and educational purposes.
Without futher ado then, here is a visual retrospective and representative sampling of the items and descriptions appearing in The Arduin Adventure.