You asked for some additional examples in which "that which" immediately follows a noun and introduces a definition of that noun. Here are five. From Thomas Kelly, "Hymn DCCXLIV," in Hymns on Various Passages of Scripture (1853):
Sweet the service (else not so),
When the servant loves his master.
'Tis to thee, O Lord, I owe
Rescue from the great disaster,
That which fell upon our race :
Mine was once a fearful case.
From "The Word of Life" in James Kernahan, ed., The Exegete and Homiletic Monthly (1880):
It is of this higher, grander life, that which reunites us to God and makes us one with Him, and in Him one with all virtuous intelligences, that the Apostle speaks in the text. To make men partakers of this life is the whole design of the word.
From a 1987 translation of The Journals of André Gide, 1889-1949: 1889-1924 (1987) [combined snippets]:
Yesterday Roger Martin du Gard came to read me the part of Les Thibault that I did not yet know. Martin du Gard incarnates in my eyes one of the highest and noblest forms of ambition: that which is accompanied by a constant effort to perfect oneself and to obtain, to demand of oneself, the most possible.
From Kent Emery & Peter Wawrykow, Christ Among the Medieval Dominicans: Representations of Christ in Texts and Images of the Order of Preachers (1998) [snippet]:
The principles thus revealed are Articles of Faith. They are incapable of discovery by the unaided human intellect, and indemonstrable by any of the human sciences. They depend for their probative force on the higher science, that which is possessed by God and the blessed, which has been revealed by the Apostles and the Prophets; the scientific arguments of theology, properly speaking, are arguments from authority.
And from Thomas Grissom, The Physicist's World: The Story of Motion and the Limits of Knowledge (Johns Hopkins University Press, 2011):
Space exists at all only by virtue of the material substance occupying it. Hence a void, or empty space, is not only impossible it is an oxymoron. The universe—that which exists—would be filled everywhere with matter as a prerequisite for its existence. If it weren't, it wouldn't exist at all.
The construction isn't especially rare, to judge from the relevant examples that turned up in connection with each NOUN + that which combination for which I ran a Google Books search.