Agreed that «vaj» seems appropriate here. You might even use it on its own here:

«*pIrun* vIychorgh tlhutlh vaj.»
= "A warrior drinks prune juice."

//loghaD
From: tlhIngan-Hol <tlhingan-hol-bounces@lists.kli.org> on behalf of Alan Anderson <qunchuy@alcaco.net>
Sent: Saturday, June 16, 2018 2:42:27 AM
To: Klingon language email discussion forum
Cc: tlhingan-hol@lists.kli.org
Subject: Re: [tlhIngan Hol] “A warrior’s drink”
 
I think this is a case where the distinction between {SuvwI'} and {vaj} makes {vaj} the better choice.

vaj Soj 'oH pIrun vIychorgh.
HoS. rach. 'Iw ghoSmoH.
(latlh ghoSmoH je, 'a DaH wIqelnISbe'.)`

-- ghunchu'wI'