Effie

That isn't exactly a great IV. Usually, Effie runs either Wary Fighter or Vengeful Fighter, which all don't require high speed. Furthermore, Effie's defense is one of her crucial stats, so -Def wouldn't be favorable. However, Effie's still a good unit, and if you have no other solid blue armors, I would still recommend using her.

You probably just started the game, right? Effie is a 3 and 4 star unit. You can build up the one you have right now then merge her into one with better IVs. You will get a few of them.

So, this is a relatively cheap build that can actually have Effie end with an offensive spread of 62/48 also bringing her Defense back up to a respectable 36. Have her support ally be to one next her to trigger her Bond also grant her +6 speed from a Rally or Tactic (if you're looking to make a Bladetome team you should already be running Tactics) will have her sitting at 54/41. The debuff from Speed Smoke drops the enemies speed by 7, allowing her to double everything but the fastest mages and swords. The 62 attack comes from a buffed attack obviously. Panic Ploy is there because I'm not all sure of the team comp. Her HP is massive, allowing her to make great use of it, especially against a Bladetome. This is far from the best she can do, too.

That's playing to her IVs, though, which isn't something you should worry about. That said, she can totally work really well like this, assuming you keep her from tome users.