Your striker, in my opinion is over two thirds the key to happy piro-mania. I agree wholeheartedly with a square spine.I've gone in another direction with this ... focusing on the ferro rods (Bayite, 6") and making sure the knife's spine is square.
Magnesium's helpful, but if you have a shower of molten steel sparks from a 6" ferro-rod, feather sticks and almost anything will ignite. The little 1/8" ferro rod on those blocks might work, but. It's satisfying when one strike throws fireworks like Mt Vesuvius.
(Which makes up for my middling skills).
AA
I have and old old scout knife and did not want to make it square I like it almost original, so I used high speed tool steel and ground it to fit the rod, somewhat, more contact area is more of your Mt Vesuvius
Yeah it means carrying 2 items instead of one, but everything fits in the fire box, knife included and drop bears only leap out at you at night drawn to the fire so the knife is out ready