So with so many great red sword lords, what is the most effective red sword in the current arena meta?
Outside of arena, which is your favorite to use?
Well fast green mages are everywhere so the best possible one would be someone with good speed, enough attack to one shot Nino/Julia, and distant counter. Ryoma is faster than Ike, whereas Ike hits very slightly harder and has better built-in skills.
Xander, however, has the advantage of benefiting from and being able to carry cavalry buffs. Cavalry teams are absurdly strong.
Zephiel can be turned into an arguably better Hector (that attack stat), but I have no need to invest heavily in him.
Eldigan is a monster of a defense unit. Combined with a dancer and Swordbreaker I actually think he's almost as threatening as Reinhardt, just not as common. His stat spread is similar to Xander and -1 special count 16 mt weapons are pretty damn good.
Ike's Heavy Blade is a fun skill to mess around with. I got a lot of mileage out of Lucina and she got me through some tough times, she was my first character with over 40 atk despite playing since launch. If my Lyn wasn't crap though, she'd be one of my favorites - her Res is actually good unlike most fast reds. Built in Desperation 2 and Galeforce can let you sweep weaker teams but her bad attack stat falters in arena and 10th stratum.
edit: shit I forgot Eirika. I wish I had one, as an avid -blade tome user.