Salaams, Heart Shape? Im not sure if you refer to the leaf pattern.. or a heart shape to a thread above mine with a heart shape on it. The leaf pattern though depicted on an Omani Khanjar appears to be originally a Persian or Indian derivative called Miri Bota(leaf pattern) adopted by the Scotish famous Paisley tie company. In the case of its inclusion on an Omani Khanjar on my thread about making Khanjars it is sometimes referred to as the eyes of the Bedouin.. as I think you will agree they do look rather eyes like... or mask like.
Formal heart shapes. Khanjars with formal heart shapes are available as Ive seen several however in my collection of about 40 Khanajer I dont have a single one ! I would say relatively common.