Perhaps the most curious development of the second season was that Shran only appeared once. A big part of what helped spark the first season creatively was his initial appearance in "The Andorian Incident" and then return in "Shadows of P'Jem." It wasn't just that Andorians returned to the franchise for the first time since the original series, but that Shran was a significant new character (portrayed by a significant guest actor, no less, Jeffrey Combs).
His appearances also provided Enterprise with the kind of light continuity that balanced the expectations of fans who'd grown to enjoy that sort of thing in Deep Space Nine (and other genre shows such as Babylon 5) and what Star Trek fans knew from other incarnations. By the time of the second season with its new approach, the crew stumbling along on its own in uncharted territory, bringing Shran back was a crucial proposition, especially the manner of which he appeared. "Cease Fire" is less about Shran, actually, and more about Vulcan-Andorian relations, which was ostensibly what the prior episodes centered on, even though Shran stole both of them.
To see him sort of take a back seat to the interspecies conflict is softened a little by the appearance of another veteran guest actor, Suzie Plakson (please don't make me tell you who she's famous for portraying, because it will only make us both look bad). The whole episode is filled with familiar faces, actually, something that was rare for the second season, with appearances by Admiral Forrest and Soval as well. In the first season there wasn't much reason to like Soval. "Cease Fire" is also notable in that it presents a different side of him as well.
Part of the point of the episode is also that Archer unwittingly stumbles into a role that he's destined to fill, and the timing of it is another indication of the deliberate shape of the season. The events of the previous season have almost become a distant memory. The second season to this point had avoided the familiar while making subtle moves at some of the more procedural developments later generations would take for granted. The relationships Archer previously formed now come back in new and important ways. Soval doesn't trust him. Shran does. To put Archer in the middle of them at the negotiating table puts all of them in a new light. Archer benefits from being able to provide a fresh perspective. Soval finds this refreshing, especially since he and every other Vulcan (except T'Pol) finds Archer to be the epitome of humanity, young and naive and hopelessly useless. "Cease Fire" is the first time he is anything but in their eyes. And for Shran, it's the first time his relationship with Archer truly proves beneficial.
It's not a monumental moment, like "The Andorian Incident," but it's an episode the second season needed, the series needed, and even the franchise benefited from. You can skip it, but you won't regret paying attention.
franchise * series * essential * character
Memory Alpha summary.