The three scrolls that Kohaku sells randomly do different types of damages, and are one-handed so you can carry a catalyst in your offhand - say, a Fox Jewel.There aren't any bows with the Catalyst tag yet but the musical instruments and the Bone Seax are non-staff/wand weapons that might fit the bill for now. Oh, and Elthara's scythe and the Fox Jewel are others but they're probably outside the theme you're going for.
That said, considering the Whitewood Bow can firefrost arrows due to being a magickal bow, you'd think it'd also be a catalyst, moreso because the elves use magick and bows despite said Whitewood bow being exceedingly rare.
It's been discussed in his Plan B thread already, but the plan is to have options to halve his 20 inches into 10, able to gain breasts to likely the size of Matiha's (pretty damn humongous melons) and/or possibly even something else or some such; it's ben discussed both from the writer and in the game from Berwyn himself that he doesn't mind or care much about his physical appearance in terms of masculine/feminine - he's even a closet buttslut and people know it.B has talked about his plans for the expansion for Berwyn that's coming up and based on that I doubt he's going to get that, more like he can be made more feminine and/or have his hyper doggy dick reduced to something smaller.