G n-grams:

鎌鼬	17219
かまいたち	180333 <- Also a comedy duo's name
カマイタチ	14778
鎌イタチ	576 <- saito
鎌いたち	372

* saito: "A flesh wound caused by some mysterious aerial influence"
* prog: "a sharp cut in the skin caused supposedly by a vacuum in the air" [note "supposedly"]

[uk]?

Also, the kokugos/gg5 use 「現象」/ "phenomenon" to describe the first sense. Might be good for us to clarify 
that as well since our gloss is very matter-of-fact and a quick skim of jawiki informs that the cause is 
disputed.

@@ -8,0 +9,4 @@
+</r_ele>
+<r_ele>
+<reb>カマイタチ</reb>
+<re_nokanji/>

Daijr: 体を物にぶつけても触れてもいないのに、鎌で切ったような切り傷ができる現象。厳寒時小さな旋風の中心に生じた真空に人体が触れて起こるといわれる。かつては、イタチのような魔獣の仕業とされた。鎌風。
GG5: “a weasel slash” (a cut in the skin from exposure to an atmospheric vacuum, a phenomenon peculiar to Japan's “snow country”).
中辞典: a cut in the skin from exposure to a vacuum formed by a cyclone.
ルミナス: cut in the skin caused by a vacuum formed by a whirlwind
https://ja.wikipedia.org/wiki/鎌鼬  "鎌鼬（かまいたち）は、日本に伝えられる妖怪、もしくはそれが起こすとされた怪異である。つむじ風に乗って現われて人を切りつける。これに出遭った人は刃物で切られたような鋭い傷を受けるが、痛みはなく、傷からは血も出ないともされる。"
https://en.wikipedia.org/wiki/Kamaitachi  "Kamaitachi (鎌鼬) is a Japanese yōkai often told about in the Kōshin'etsu region, and can also refer to the strange events that this creature causes."

The current version is from 2010, when Scott entered it and commented: "gg5's explanation is quite funny (an inaccurate)." No reference.
So the dictionaries say it's the injury and Wikipedia concentrates on the mythical beast(s). Here's my version. Not sure an xref to 妖怪 is needed/appropriate.

@@ -12 +12 @@
-<gloss>type Japanese folkloric monster (yokai), thought to be a trio of weasels who appear in a whirlwind to cut their victim</gloss>
+<gloss>cut in the skin caused by a vacuum formed by a whirlwind</gloss>
@@ -16 +16 @@
-<gloss>cut caused by whirlwind</gloss>
+<gloss>mythical weasel-like creatures riding on whirlwinds and inflicting sharp, painless wounds</gloss>