For the first, the verb is definitely an imperative ("tsuyoku nare"), so it's Rukia who told Ichigo to become stronger, and Rukia who was defeated. For the second, there is no subject in the original Japanese, so although the sentence obviously refers to Ichigo you can't precisely say "I" or "you" or "he". ^^;

...Probably in this case "he" is the best translation after all, because it's neither from Orihime's nor Ichigo's nor any of the characters' POV. The stuff that runs along the side of the page in WJ chapters is editorial commentary. XD

So now that I think about it, the most precise translation would be along the lines of "Become strong" - the one who said that has fallen. Once again, he could not protect her...