I was wondering whether the Gothic weak nom.acc. manna was actually originally a strong dative, seeing that many of the occurrences are with preterito-presents, eg here
(search for 'manna' in
http://www.wulfila.be/Corpus/Find.asp )
Matth 6,24
manna mag
Matthew 8:28
ni mahta manna
John 6:44
manna mag
John 7:27
ni manna wait
John 9:4
ni manna mag
etc
in which case those preterito-presents were perhaps once intransitive construed with datives, cf
Russian mne moz^no "I may" (= Proto-Goth. mis mag ?)
Torsten