Perhaps I am reading these scriptures wrong, but I draw a different conclusion from these:
1st Peter 1:3 through 12 KJV
3 Blessed be the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
4 To an inheritance incorruptible, and undefiled, and that fadeth not away, reserved in heaven for you,
5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
6 Wherein ye greatly rejoice, though now for a season, if need be, ye are in heaviness through manifold temptations:
7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ:
8 Whom having not seen, ye love; in whom, though now ye see him not, yet believing, ye rejoice with joy unspeakable and full of glory:
9 Receiving the end of your faith, even the salvation of your souls.
10 Of which salvation the prophets have enquired and searched diligently, who prophesied of the grace that should come unto you:
11 Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.
12 Unto whom it was revealed, that not unto themselves, but unto us they did minister the things, which are now reported unto you by them that have preached the gospel unto you with the Holy Ghost sent down from heaven; which things the angels desire to look into.
Perhaps I misread; but from the preceding Scriptures in which I have highlighted those things to which I believe that statement referes.