==ALWAYS BACK UP YOUR FILES BEFORE INSTALLING A MOD==
How to install:

Go to the Tactics Ogre Reborn directory on your system. It is usually under Steam/Games/Tactics Ogre Reborn. Go to the Data folder
Make a backup copy of Filetable.bin. Go to Battle (in the data folder) and make a copy of battle_data_release.dat. 
This should back up the original game files and make it easy to revert to them by replacing the modded files with them at any time.

Select the mod data set you would like to install in a different window. (Such as Armor Unbound, Skills Unbound, etc) 
Copy the filetable.bin file, and paste it in Tactics Ogre Reborn/Data. Copy the battle_data_release from the mod folder and paste
it in Tactics Ogre Reborn/Data/battle. 
This should succesfully install the mod. 

Every entry of Unbound is self explanatory. 
Unbound weapons removes all class requirements for weapons and gives all classes access to the respective weapon proficency skill.
Unbound skills gives all classes access to all skills - NOT including weapon skills since they don't work like that.
Unbound armor is the same as weapons, but for armor AND shields. 
Unbound spells gives all casting classes access to all spells. This does not give classes that could not previously cast spells access to spellcasting.
There are several combination data files that emulate multiple data sets at once, that are all self explanatory.
Unbound weapons and skills will remove all class requirements for weapons as well as skills, and so on.