I wouldn't call it a "weak strike", more accurately, some of the design elements are weak or, in some cases, non-existent with a grease filled die. A weak strike more often refers to inadequate die pressures, worn dies or dies spaced too far apart. Yes, those "scratches" are what we call planchets marks. Generally blank planchets are pretty rough with lots of small scratches on them. The mint relies on the die pressure to smooth them out. However, if the dies are spaced too far apart, metal will still flow into the die recesses but not fully into the deep parts. Most of us believe those scratches were on the planchets prior to striking and they remain there after the coin is struck.
Despite there being a couple letters not totally sharp, this is still a very well struck coin. Every detail is there if not always the strongest. There are only a couple tiny nicks and some real nice luster. NGC settled on a 66. IMO, they were dead on.
Would NGC/PCGS give it a 67. Very doubtful. I am pretty sure it has seen some MS70. But it is pretty well nick free, nice strike, I give it a + for eye appeal, but it lacks a bit of luster (mostly on the reverse) for a 67. 66? or maybe a 66*