Wa 3alykum assalam
There does seem to be a confirmation from brother Joseph that the conjunction "wa" does seem to be used in different ways other than the mean "and"
One way it is used is, to elucidate/clarify existing statements as shown by the excerpt below.
UNDERSTANDING THE CONJUNCTION 'WA' (AND)
015:087
"And certainly, We have given you seven / several of the oft-repeated and (Arabic: wa) the great Quran"
Some Muslims understand the conjunction 'wa' (and) as an indication to imply something separate from the main Quran. Such an assertion takes little account of the Quranic style of dialogue which clearly uses the conjunction 'wa' in different ways.
Not only is 'wa' used in the Quran to denote something separate or additional, it is also used to elucidate an existing statement by defining it or clarifying it.
For example, in the following verse, we note:
055:068
"In both of them (are) fruits (Arabic: fakihatun) and (wa) date-palms and (wa) pomegranates"
Here the conjunction 'wa' (and) when used with date-palms and pomegranates only clarifies the 'fruits' and is not read as separate from the category of fruits (fakihatun).
Similarly, in verse 15:87 the 'great Quran' is only an elucidation of the 'several oft-repeated' description that has been used to describe its central core message.
[1]Also we note that many chapters start with the letter "wa" like chapters 89,91,92,93,95,100,103.
This can easily been seen as an "oath" being taken. So the letter "wa" seems to more rightly mean "By" rather than the general meaning "and".
Insha'Allah that helps in some way
Salam
[1] THE SEVEN OFT-REPEATED
http://quransmessage.com/articles/oft-repeated%20FM3.htm