With "full split bands" NGC or PCGS qualifying condition. It may command a market MS65 grade with "weak strike" unique toning.? I've seen worse! JMHO
If you're listing it for sale/ auction I would not specify. Buyer/ bidders make the call.. Or roll the dice and send it in to be graded. You seem to have a history of excellent results....
The approach is really the same as any other coin - is there wear on the high points? Is the luster disturbed on her cheek, ears, hair, or on the bands of the fasces? Is there disruption of luster in the fields? Based on what I see in the pictures, I don't see any high-point breaks or disturbance of luster. Looks like an MS coin to me.
The toning on that one makes this one a bit difficult. There is a little bit of scuffing on the Fasces. But, it is minor and probably from bag contact. I am leaning towards MS.
Sometimes the difference between AU58 and MS64 is closer than between AU58 and MS60. Odd, but true. It may boil down to whether the observer sees cabinet friction or rub or nothing. Cabinet friction - Acceptable rub from care and storage. Usually applied to softer copper. Rub - wear from circulation. Nothing - Not detectable or bad eyes.
Not hard to understand, as they're totally different grading criteria. If the questionable AU58 is beat up all to hell, then it sneaks in at the lower MS grades.
Between the poor strike (even for this poorly struck date) the long graze in the NW quadrant and the chatter in the SE quadrant on the reverse I think the graders would be conservative . . . MS63. I don't think this is an AU coin.
If you want to be really picky, it has a rub on the front of Ms. Mercury's cheek. The graders will probably ignore that, but they can't ignore the weak strike on the date and the left side of "in God we trust." My hope would be MS-63, since that is really a fair grade for the piece, marketwise. The grade could go as low as MS-62.
That's a greased motto and greased date. Even the reverse has remnants of it. They were going with these dies beyond their useful life, over-lubricating them in lieu of working them. The striations tell they let them go. I don't think their market is going to like that motto and date, I'm with you on that, I think they'll deduct on the grade for it.
I agree with your observation, stating "a weak strike", occasionally caused by lubrication displacement. JMHO
In cases like this I like to pull out my copy of Halperin's book, How to Grade US Coins; according to page 105, the high points of the designs are: obv: center of cheek, and about the midpoint of the wing, just behind where the ear should be; on the rev, the midpoint of the diagonal bands on the fasces. I don't see any smooth gray wear in either area so conclude it's MS.