D&C 76

In this vision, the Lord describes the people and conditions that qualify and limit those that will obtain Terrestial Glory or how it compares to the glory of Celestial glory where  -

"...that of the moon differs from the sun in the firmament."  (Doctrine and Covenants | Section 76:71)

First, it appears the Lord describes a group of people that may qualify or be limited to this glory, teaching -

"...these are they who died without law;
73 And also they who are the spirits of men kept in prison, whom the Son visited, and preached the gospel unto them, that they might be judged according to men in the flesh;
74 Who received not the testimony of Jesus in the flesh, but afterwards received it."  (Doctrine and Covenants | Section 76:72 - 74)

Thus, one group of people could be those who died without learning the laws and ordinances of the gospel while on earth, but later received the testimony of Jesus Christ in the world of spirits.  Receiving the testimony of Jesus Christ suggests the they come to know or receive a witness that Jesus is the Christ but does not necessarily suggest that there is acceptance, repentance, and obedience to the gospel of Jesus Christ.  I would also add that many of these may be those that chose to not seek or learn about His law which means they would end up without His law.

The Lord then describes another group of people that may qualify or be limited to this glory -

These are they who are honorable men of the earth, who were blinded by the craftiness of men."  (Doctrine and Covenants | Section 76:75)

The reference of this group is particularly related to life as a mortal.  Blindness by the craftiness of men would be in my mind, those that may have been mislead by the craftiness of priestcraft (2 Nephi 26:29).  It is then that the Lord combines or summarizes all these people and their individual circumstances whether in this life or in the world of spirit where -

"These are they who are not valiant in the testimony of Jesus..."  (Doctrine and Covenants | Section 76:79)

This makes it clear of those that will obtain or be limited to terrestial glory.  It is those that receive the testimony of Jesus in this life or the next, those that are honorable men suggesting living good and moral lives but never are willing to be valiant in the testimony of Jesus meaning that there is really no willingness for conversion, continual repentance, receiving the saving ordinances of the gospel and enduring to the end by striving to keep the commandments of the Lord.