I came across this essay from former U of U history professor and LDS Church historian Davis Bitton. http://publications.mi.byu.edu/publications/review/16/2/S00017-5176ad2f5804e17Bitton.pdf
The main thrust of the essay is that it is essential to have a testimony of the gospel of Jesus Christ, not a testimony of a historical narrative, and discussion of how those two concepts are different and interrelated.
One key concept that has frequently crossed my mind is the idea stated on page 339 that, even if I (as a non-historian) cannot answer the problematic questions in church history, I know there are historians who have wresteled with them and retained their testimonies of the Gospel. Maybe that feels like "leaning on the arm of man", but I don't feel that it is necessary for me to become an expert in every possible branch of study. I frequently find that it is sufficient for me to know that others have wrestled and are wrestling with church history and finding their faith intact.
The other key concept that I resonated with me was the importance of grounding my testimony in the Gospel of Jesus Christ. When pressed, I will usually cite Helaman 5:12 as my favorite scripture, because of Helaman's teaching that we must build our foundation on Christ and none other. Church history is interesting, and it describes a story of how the restored Gospel came to man in these latter-days (complete with human foibles and frailties), but it is not the Gospel.