Roger Ascham his language

As I was finishing Ascham's "Toxophilus" I've stumbled over this phrase, the meaning of which remained unclear to me: "An other wil stand poyntinge his shafte at the marke a good whyle and by and by he wyll gyue hym a whip, and awaye or a man wite". The context can be seen here.

I came to understand the phrase thus: "Another will stand pointing his arrow at the target for a good while and on and on he will give himself a whip (on the arm?) and go away before anyone should know".

I'm not sure, however. Firstly, what does the pronoun "him" refer to? Does it denote an archer? Ascham uses "himself" quite regularly in similar cases, e.g. "defend his country, and save himself from his enemy", "archer ought to provide for himself" etc. Why not here? "Him" could possibly be applied to the shaft, although I have trouble imagining how one would go about flogging an arrow. At first I thought maybe by a "whip" Ascham meant an act of loosing an arrow, but "whip" must mean "a blow or stroke with, or as with, a whip", since Oxford English Dictionary uses this particular sentence to illustrate the meaning. Even though I have some thoughts as to how standing with an arrow drawn can result in an injury, still it feels like a conjecture.

"By and by" could alternatively mean "consequently", or "soon" even, so it doesn't really clear things up.

Finally, I'm at a loss regarding why Ascham would put "wit" in a subjunctive mood. Does it add any peculiar meaning to the sentence? Does the archer in question try to leave before anybody takes notice of his awkward shooting? Or is it just a phrase meaning "very shortly"? Why then not say "or a man wot" instead?

So, am I the only nitwit who's confused by Ascham's usage of English or is it a genuinely complicated phrase allowing for interpretation? I'm eager to know.

P.S. As a bonus question, what's the meaning of the preposition "of" in a phrase: "All the discommodities ... [can not be] soon reckoned of me, they be so many." Same source. I couldn't find a similar usage of the word anywhere.

whip might be used either in reference to the shaft/bow or (as pointed out by chasly in the comment) to his person, and this in the sense of jolt, a sudden movement. (The usage of whip in the sense of "move fast or suddenly" can be traced back to the 18th century (at least, didn't have time for searching further), as in "whipping up the stairs".) away, meanwhile, may allude to the shaft being loosened:

"Another will stand pointing his arrow at the target for a good while and after some time he'll make a sudden movement and the arrow is gone before anyone should know".

or

"Another will stand pointing his arrow at the target for a good while and after some time he'll suddenly loosen the arrow, and it is gone before anyone should know".

This is, of course, interpretative guesswork for now, and might be completely off the mark (no pun).