Why would Russia's reaction be especially important/significant? I think Russian reaction due to seeing Ethiopians as their Orthodox brothers is a bit of a stretch.
No Rastafarian religion ITTL.
The real question is how this affects the rise of Italian fascism.
Welcome to the board. Italian fascism would likely not occur even if they lost in a slightly different way due to the butterfly effect essentially wiping the historical plate clean, so it's kind of irrelevent.
As for the topic itself; it seems spies sent by Ras Alula (Emperor Menelik's chief military adviser) were responsible for alerting the Ethiopian emperor to the Italian advance. The Ethiopians still outnumbered the Italians over 5 times, but should the spies be killed or captured by Italian troops or Italian spies, and word is sent that the Italians should press their attack, then maybe the surprise could lead to some alternative consequences.
However, the Italian weaponry and communications were outdated as hell; that's not to say the Ethiopians had it better, but the Italians weren't exactly up for it. Morale was also low.