occasion is preceded by the word
one. There is therefore no possibility that occasion
s could be correct.
A comma would not change the meaning of the sentence, but I would leave it out.
Personally I don't pause after
occasion. I do, however, make '
on more than one occasion' a tonal grouping.
The second sentence is wrong. It should read 'he almost killed'
and not 'almost he killed'. (Frequency adverbs go between the
subject and the verb.) Thus modified, it means the same thing as
the first sentence.
The third sentence doesn't work somehow. It says (to me) that the
moment came when he was on the verge of killing Tiberius -- his sword
was raised high, and he was about to plunge it into Tiberius. And
at that very moment (not before) his anger overwhelmed him. That
doesn't make sense. Compare:
I was about to leave the house to do my grocery shopping when the phone rang.
CJ