Possibly an alternative form of whistly, or whishtly (“quietly”).
wistly (comparative more wistly, superlative most wistly)
- (obsolete) In an intent manner, intently; with close attention, attentively
2007, Peter Marshall, Mother Leakey and the Bishop: A Ghost Story, Oxford Univ. Press, ISBN 9780199273713:
- … which makes him eye this gentlewoman a little more wistly …