Source: STC 1972 = UMI ID#99840299
Author: Best, George, d. 1584.
Title: A true discourse of the late voyages of discouerie ... vnder the conduct of Martin Frobisher
Q. "Should we capture this as "∵" or ignore it?
A. This looks like a typographic ornament to me, not a functional text character. It is certainly not performing the function of a "because" logical operator. Ignore it.
Source: STC 25440 = UMI ID#99854909
Author: Whitney, Isabella.
Title: A sweet nosgay, or pleasant posye
Q. "Should we record this as "&rindx;"?
Q. "Should we record this as "⋆"?
A. No. For one thing, "⋆" is really meant to be used only for the special math symbol (binary operator) that looks similar, not just any star. For another, a five- pointed blacked-in star is a very typical form taken by the ordinary asterisk in early printing.
I would capture this simply as asterisk (*), both here and elsewhere in the book, where it is often used to mark the beginning of paragraphs, etc.