As nobody seems to be answering... this is just a suggestion, but when you look up in a medical dictionary (such as the one I list below, and look under the column 'knife'), you get a lot of different types of knives bearing names of their inventors. Now, amongst those knives listed, for instance Kirkland knife is usually called カークランド・ナイフ or カークランド鋏 in Japanese, and Goldman-Fox knife is ゴールドマン＝フォックス・ナイフ or　ゴールドマン＝フォックス・メス (both are used in dentistry and come in various sizes and shapes). So I think it is quite probable that there is no translation for Humby knife either other than just to call it ハンビー・ナイフ (or maybe ハンビー・メス, from what I could see from various sites with photographs of Humby knives, they are more like メス than 鋏).

just a suggestion but hope this gives you some idea...

http://www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspzQzp...