I'm not a lawyer but I am a knife collector and I've lived in quite a few locations (including Kalifornia.) To the best of my knowledge, "blood grooves" are not illegal anywhere in the USA. The primary reason is that these grooves down the sides of blades are not for "blood" at all.
Blade grooves are technically called "fullers" and are a structural addition to the blade, placed there by skilled blade smiths. Engineeringly, they are not exactly the same but they are akin to the convolutions in corrugated sheet metal. Without the ridges (humps and grooves) the sheet metal bends easily. If you form the ridges, the thin sheet metal can be strong enough to be a roof.
Bottom line: collect them without fear (however, don't try to carry them around in public, in CA.)
The term blood groove is an American colloquialism and means nothing. We've all heard that the groove is made to allow blood to flow in a deep cut, but this is simply an uneducated attempt at describing the fuller. The fuller is named for the special hammer and anvil tool set (a fuller) used by a blacksmith to produce the groove that spreads hot iron. The word cannelure is probably the best descriptive word for this feature, as it simply means "to groove."
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