A verb appearing as ᴹQ. rista- “cut” in The Etymologies of the 1930s under the root ᴹ√RIS “slash, rip” (Ety/RIS).

A similar set of forms “rista & risse, rinse” appeared in notes on Words, Phrases and Passages from the Lord of the Rings (WP) from the late 1950s or early 1960s derived from √RIS “cut” as part of a discussion of the etymology of S. Imladris (PE17/87). These could be various noun or adjective forms, equivalent to the final element of Imladris, but in that note Tolkien said that Sindarin element was derived from primitive ✶rinsa “cleft, cloven, separate”. Therefore, I think these Quenya forms might instead be a formative or causative verb rista- “*to cut” with strong pasts risse or rinse.

Neo-Quenya: Given the uncertain nature of the forms from WP, I would assume rista- is (or became) an ordinary weak verb for purposes of Neo-Quenya, with a past form *ristane. Given the meaning of its 1930s root (“slash, rip”), I would further assume its connotation is “cut [into]” as opposed to Q. cir- “cut completely, cut apart”.