This might be a controversial assertion, but I don't think the sign of Libra alone is all that skilled in the creation of peace. Libra is the peacekeeper, maybe. But peacemaker? Peace creator? No.
Libra can often maintain, through its slick social skills and airy diplomacy, a form of peace that has already been established, but getting to a state of real peace often involves getting into it, and Libra is a sign that, especially when squared by Cancer or Capricorn, prefers to avoid that unpleasantness.
This avoidance is problematic because getting to a real state of peace often involves complex and longstanding disputes, injustices, imbalances, injuries, and instances of oppression that have been hidden, covered over, smoothed over, let slide, reinforced - made worse, in fact, by Libra's glossing over of realities and nervous insistence on everything staying nicey-nice.
Slapping a Band-Aid on it and forcing a phony handshake over drinks without addressing underlying issues is not the recipe for true, longstanding justice or the peace that stems from that. Keeping everything Libran light and pleasant isn't really the goal when you get right down to it - getting to the root of the discord and injustice is, as well as to a mutual understanding of what caused and continues to cause these things so they can be addressed and the chains broken.
The drawing up and divining sign of Scorpio, then, becomes instrumental in the process of peace creation. The road to peace might be initiated in cardinal air Libra, but it's fixed water Scorpio that digs in and takes the process beneath the surface, where it needs to go to be truly effective.
It's the catalytic power of expressing the raw human experiences of millennia of suppression on this planet, especially emotional and psychological realities, that starts the process toward real peace, equality, and harmony. If we can't get to and express the core realities, we don't get to any real healing, peace, or understanding.
With Scorpio, there is right and wrong, good and evil, just and unjust - and these cut-and-dry distinctions can make Libra, which at times searches for common ground that does not exist, very uncomfortable. This is part of the reason why Venus, Libra's ruling planet, is considered to be in its detriment in Scorpio.
Scorpio is a sign that is, or rather, can become, fully aware of core realities and hidden dynamics, especially of the domination/subjugation variety. Skilled Scorpionic types (whether that be a strong Scorpio contingent, a strong Pluto, a strong 8th house, or a combination) can feel a subtle energetic disruption that most other people wouldn't have the radar to pick up, and they can follow that disruption right to the root via sheer intuition.
Scorpionic or Plutonic people can understand the root causes of behaviour that others would write off as bizarre or extreme - especially when that behaviour is an expression of collectively-reinforced repressive/oppressive dynamics. Scorpio understands that at a certain level of collective denial, the pressure on the individuals with awareness cannot be contained any longer, and it erupts. Scorpio is a sign associated with volcanic eruptions and also nuclear meltdowns of the emotional variety.
