[Guido]

I could have not mind much the subplot about Mr. Wantz, but Oland's performance became emotional that I sympathized with his point of view.

Oland is afraid of being unable to save lives, watching helplessly how people are so frail. He commited monstrous atrocities in his past and regretted every single of it.
Light came when he arrived and was accepted in Section III, because he's now made precious comrades which gave him peace of heart. Yet, still his past looms on him as a shadow of dread to remind him that there's a killer inside his soul.

Oland wishes to redeem himself by making a better country serving under Section III; I guess he understands how tough and brutal was for Mr. Wantz to have dedicated a good portion of his life doing the same thing over and over but not getting anything for it.

This subplot just feels to me not contributing much with the pacing and storytelling except for making clear three details:
1. Oland regrets his past actions.
2. He spent a deal of his life serving as a killing machine, obeying orders without question.
3. He now wants to right his wrongs and comes to appreciate that he's not alone, he has comrades. However, it is imperative to him to start walking the path he chooses for himself and not resorting to the ways of his past.
Which I presume it would be almost impossible, unless he goes searching for the truth of his nature.

Animation-wise the episode dropped in quality for that department, but story-wise introduced several key story elements.

Spoiler:

1. Machs and Oreld were the stars for this episode. As long as you're a member of Section III, then you're like family. That's my interpretation Among comrades there are secrets that must be told but others that should be kept secret even to friends. Oreld taught to Machs that someone's past is not to be intruded upon.
2. Despite his womanizing ways, Oreld has the touch and communication skills to retrieve the confidential data even he's become a lucky bastard, securing a kiss from Mireille.
3. The data reveals that Oland's admission to Section III was requested and insisted by the Kauplan Institute.
4. The Kauplan Institute must be the shadow organization behind the development of the 901-ATT unit and owner with every affairs related to the Invisible 9. It is still uncertain early at this point, if they are other groups pulling the strings behind the Empire, but for now K.I. is the first known antagonist.
5. Dr. Muse Kauplan, the scientist woman seen at the start of the episode four testing on what looks to be 901-ATT trooper just like Oland is. Upon Section 3's discovery of the gattling tank, plus Cpt. Hunks reports about the mysterious foot soldiers, I'm afraid Dr. Kaplan has stepped into the stage to deter Section 3's from gaining any further information.
In other words, sooner or later she's going to make her move in order to silence Section 3 or have it disbanded.