Stormed at with shot and shell, While horse and hero fell. (lines 43-4)
More intense imagery, filled with the weight and the sadness of death. In a way, death is always in the air in this poem, and here it literally is. It's whizzing through the air in an angry storm around the heads of the soldiers. They get cut down, and that simple "horse and hero fell" is about the only moment where we have to confront the actual death of the soldiers in the Light Brigade. Here death isn't just a metaphor, it's the actual fact of a soldier getting cut down.
All that was left of them, Left of six hundred. (line 48-9)
Tennyson is very quiet about how many men died. In fact it's almost like it's a secret. Well, maybe more a kind of respectful distance. This isn't about the number killed and wounded. It's not a newspaper article, after all. It's about the fact of sacrifice and the death of brave young men.