The Barioth armor is great armor boasting a high defense and the Evasion+2 skill making it ideal for Longsword, Switch Axe and Hammer users whom lack a shield to defend with as well as those wanting to "Evade Lance"
The Barioth armor is not often seen during low rank because many players struggle with the difficulty of defeating a Barioth at this time. However this is a very useful armor due to the Evasion +2 skill which will give around an extra 10 invulnerability frames during rolling and side stepping, allowing feats such as rolling through monster roars, hip checks and much more.
Marathon Runner is helpful especially to hammer users as it also slows stamina drain during super pound charging.
Decorations will be limited to this armor as it only has 4 slots, many will be tempted to add in fire resistance +10, this is not at all necessary as with Evasion+2 you will easily be able to roll through Rathalos/Rathian fireballs, Agnaktor heat beams, Qurupeco's flint stone attack, and Uragaan heat waves, the only fire attacks present during low rank.
Good skills with Barioth Armor would be any C-skill (e.g. Speed Sharpen and Capture Guru) which only require 5 decorations so you would only need a 1 slot charm or a 1 slot weapon, if you have a spare slot you can also gem out Heatsurge (Lo) by adding 1 Breeze Jewel but this is not crucial as Heat can be cancelled by simply taking a Cool Drink (But you will still take extra damage if you stand in lava!).