Help with Ike

Actuall a -spd is actually good for him, Ike is one of the few units that ca benefit from a - or + in a certain stat(IN Ike's case it's speed, you can make a slow Ike with -spd or you can make a fast Ike with +spd, and it's all ok)
With + atk he'll make use of Heavy blade much better but I recommend the Seal if you are going to give Ike an A slot skill to boost his attack.
(Numbers of A skill will indicate which other skills with best with the A skill)
Weapon:Ragnell
Special:Aether
A:Fury3(1), Deathblow3(2), Sturdy(Blow or stance)(3) or Heavy blade(4),
B:QR(1,3,4),Sword breaker(1,3,4),Vantage(1,3,4),Renewal(all)
C:Flexible
Seal:+atk/def/res,Close(3) or distant defense(1),Heavy blade(1,2,3),QR(2,4,renewal)

I think your best bet for those IVs is going Heavy Blade+Quick Riposte/Swordbreaker as your B skill(his seal should probably be Distant Defense, at least if he’s going to be the main DC unit). Use Aether as your special, you’ll be able to proc it right away in the next turn.

You can also go for Steady/Warding Breath instead of Heavy Blade, but they are a bit more expensive.