Spare Ike

Imo the only characters that can sacrifice their a slots with minimal suffering to their actual best builds are the 1 shot cavalry blade mages of Leo and Cecilia only. The problem is...Deathblow 3 is still almost always better for them anyways...

TBH, Heavy Blade is a high charge gimmik skill that should only be on people like Ike and only because it gives him the Aether charge to kill and heal himself back up (that or maybe galeforce) and it's truthfully its just not all that much better than other A slot skills for most character...

If anything he's better fodder for Swordbreaker 3

I used to have a +HP -Atk Ike. Then I pulled three more in Hero Fest and now he's +Def -Res +3. Ike isn't great for inheritance really. Just make him as buff as possible.

It's rare, so in some ways it is worth keeping if you think tou might inherit Aether or Heavy Blade in the future. However, as the other guys have stated, it's not the most optimal A-Slot by any means and is just for fun on other characters.

I would personally merge Ike, as his standard Heavy Blade set actually has a higher arena rating than most due to the SP cost of his skills, thus allowing Ike to gain more value for arena from merges than some other heroes.

Hope this helps.