other than a fuse for lightning
A fuse is not likely to provide much lightning protection. The bare minimum is to ground the antenna installation to NEC requirements then apply addition surge protection as desired.
Again,
three tier antenna as a description for the evaluation of antenna performance can be somewhat lacking.
Here is the thing, not all antennas are created equal. Again not all antennas are created equal. Some are very poor at FM broadcast band frequencies above about 92 MHz for a number of well known technical reasons.
Depending on what was needed for a given location, a three tier antenna could be three VHF high band ( that work at 216 MHz and above) antennas that would be quite poor for FM broadcast band reception.
I'm talking three stacks of antenna with about two feet separating the layers and angled in different directions.
Again, three tier is not a technical description of antenna performance. What you are describing is just the use of multiple antennas, in this case three, to be able to receive stations from different directions. This is done because as you posted they are pointed in different directions. This is done so that an antenna rotator is not needed. That is all.
To be clear, stacked antennas can be used to increase gain if they are
all pointed in the same direction and implemented correctly. Adding a second identical antenna will gain about 3 dB and adding a third antenna will gain about another 1.5 dB. at the antennas design frequency range.
And whether or not an amplifier is needed depends on the amount of signal as seem by the antenna, the feed line loss and loss due to splitting the signal if it is split.
Again, I am not trying to be the TV antenna use for FM broadcast band reception police, but making broad blanket statements with references using a technical descriptor such as
three tier leaves a lot to be desired because it means nothing in terms of how well it will meet the particular reception needs in a given situation.
As rcs16 mentioned, a picture may help if you do not not the brand and model number.