bhagavaa - nominative of bhagavant, "the Blessed One"
tassa sattaahassa - genitive, "of that seven days," "of that week"
accayena - instrumental, "with the ending"
tamhaa samaadhimhaa - ablative "from that samaadhi," "from that
concentration meditation. This is one that for people who know a
little about Buddhism it would be best to leave untranslated
as "samaadhi" but I see that at Access to Insight they translate it
(in the prior parts of the Udaana) as "concentration."
vu.t.thaasi - aorist, 3rd person singular, "arose," "rose out
of," "roused himself"
So:
"Then the Blessed One, with the ending of that seven days, arose from
that concentration."