True enough. 'weka' does indeed function as an intransitive verb, meaning "be absent, away", and as a transitive verb, meaning "cause to be away, discard, rescue," etc. But not directly "go away" (I suppose 'o weka' implies some motion but doesn't strictly refer to it). To be sure, things like 'sewi' (which is a noun, not an adjective, of course, but still....) do come to mean "go topward, up" , apparently by ellipsis from the causative transitive reflexive 'sewi e sama' "causes itself to be above" (with the usual casual adjustments). So, maybe the same could happen with 'weka'. I'm just not sure it has happened yet. And, in the meantime, both 'kama weka' and 'tawa weka' are around and transparent.