Not seeing how Diana keeps this Sentry down. You need some really weird esoteric stuff I feel. Lasso would probably work though (Sentry won't break free with strength, but he might tear himself apart and slip through).
This Sentry also has some crazy strength feats (the Exitar one), and can hurt Wonder Woman (eyeblasts that OHKO Thor will hurt her without bracers, and EVENTUALLY they'll start wearing her down).
Split IMO. Diana can't really hurt Sentry, but she can probably bind him, is strong and skilled enough and has the perfect thing to do so, and is tough enough to stand toe-to-toe with Sentry for some time.