I haven't been seeing much talk about Catherine, but I feel like there are many advantages to using her. Mainly, even though she comes a little late, she's strong from the moment you get her. I'll be talking as if you recruit her in chapter 4, since that's when she most obviously shines. She has A swords, 19 strength, 20 speed, 13 defense, and swordfaire, all while starting at level 11 with solid growths. She's better than most of your units at chapter 4 at least, and stat wise, she's usable throughout the entire game, staying strong. She's basically an FE4 prepromote.
She definitely has major movement problems though. Since she comes late, it's even harder to get her E flying to B+ for falcon knight, and assassin is way easier to get, but only 6 move. Despite that, I wanted to talk about her strengths since I feel like I don't see them getting mentioned enough. Interested to see the discussion