Hi, Derek, Rick, and Modest Observer,

DC> Maybe its an adverb/accusative of manner. The PED says it can also
DC> mean pleasure, pleasantness, enjoyment (in general) rather than just
DC> sensual pleasure (in particular).

DC> So ... "pleasurably in him place your confidence"

DC> Or ... "gladly place your confidence in him"

DC> or something like that?

Yasmi.m mano nivisati, cittaсcaapi pasiidati.
adi.t.thapubbake pose, kaama.m tasmimpi vissaseti.

Commentary says:

Kaama.m tasmimpi vissaseti - anubhuuta pubba sinehe neva
tasmimpi puggale eka.msena vissase, vissaasa.m aapajjatiyevaati attho.

and thus equals 'kaama' to 'sineha', affection, love.

kaama.m tasmimpi vissaseti - trust such one with affection.

which preserves the original ambiguity of 'trust while feeling
affection' and 'trust that he will come up to your affection'.

The man, on whom, though never seen before,
your mind is settled and your heart is brightened -
trust him with affection.

Dimitry