Shalom,   Love your neighbor as yourself is the key precept to consider and wearing something immodest that draws attention to oneself is certainly problematic but going to gehennom for short sleeves is a stretch.   Why because we are judged relative to our generation.  There was a time in Jerusalem some centuries ago were harsh decrees were placed on the city in heaven because the women who were uniformly  what today would be called ultra orthodox began experimenting with belts on their skirts which would show case their figures This would be completely acceptable for wives of rabbis today but in that generation it was too risqué. So everything’s relative to the generation and wearing a short sleeve would not = gehennom