[nescioquid]

Some words in Shakespeare have different meanings today or have simply left standard usage. I don't think the presence of a word in Shakespeare means it is de facto good style to use today.

From a correctness stand-point, I think a descriptionist would be satisfied with an attested usage, especially from such a source. From a style point of view, I still find myself feeling embarrassed for the author when I encounter this usage (which is my own problem).