A verb that first appeared in the Outline of Phonetic Development (OP1) from the 1940s as ᴹQ. raphe “seizes”, with past tense rappe “seized” illustrating the phonetic development of mph to pp (PE19/45). The verb reappeared in the Quenya Verbal System (QVS) from 1948 as a derivative of the root ᴹ√RAPH “snatch”, again to illustrate the past tense of basic verbs whose stems primitively ended in ph (PE22/102).
The verb appeared yet again in the Outline of Phonology (OP2) from the early 1950s illustrating the same sound change, but there Tolkien changed the gloss of the verb to “waves, brandishes” (PE19/89). In green-ink revisions to OP2 from around 1970, Tolkien gave the meaning of the root as √RAPH “seize, grab” with a derived noun arpo “seizer, thief” (PE19/89 and note #101), so it seems the meaning “brandish” was a transient idea.
Neo-Quenya: For purposes of Neo-Quenya, I would use raf- to mean “snatch, seize” based on the restored 1970 meaning of the root.
The root ᴹ√RAPH “snatch” itself first appeared in the Quenya Verbal System with a derived verb of ᴹQ. raf- of the same meaning (PE22/102), but it might have been a reemergence of the very first (deleted) gloss of the early root ᴱ√RAPA the Qenya Lexicon of the 1910s: “handle hastily, snatch, grab” (QL/79). As for √RAPH, it reappeared in green-ink revisions to the Outline of Phonology (OP2) from around 1970 with the gloss “seize, grab” and a derivative Q. arpo “seizer, thief” (PE19/89 and note #101). On the original layer of composition for the same page (and therefore from the early 1950s) there is the verb Q. raf- “wave, brandish” which may be related, though if so it must represent some semantic drift (PE19/89).