I am setting up Rise of the Runelords Anniversary edition and I was curious as to how I should tell my PC's what this +1 repeating crossbows worth is and if there are any special abilities tied to it. From the text it sounds to "epic" to not have some other ability than a +1 Attack Bonus. Also would I just treat it as a heavy crossbow for damage or does this have it's own requirements? The book is not very clear on any detail regarding it for referencing. The way this sounds by it being a +1 it's just a masterwork item that has a custom grip? Any ideas on pricing or ability scores?
As-written, it should be treated as a standard magic +1 repeating crossbow. (Any item that says it is "+1" or some other number is magical.) Repeating crossbows come in a couple sizes (hand, light, & heavy) which will determine the base damage. (Information on mundane variants can be found here ). Add a +1 enhancement bonus to attack and damage rolls made with the weapon.
The often forgotten thing here is that a lot of magic items are not mundane looking. Considering the price of making the weapon masterwork and magical, a little customization is a negligible additional cost.
An example that illustrates this from the magic item creation rules:
In fact 30% of all randomly generated magic weapons are visibly magical: