Again, I’d suggest you go out and actually play with them for a bit. In realistic scenarios, you’re getting the majority of your damage from the charge/splash damage. Go try chasing down archers, for example; the closest unit dies, generally, after getting off a single attack. If that attack did 9-12 damage, it’s completely worthless. It’s only because it does 20-30 damage and splashes across multiple targets that it has any value whatsoever.
Honestly, the fact that you’d even suggest getting rid of what is objectively the only redeeming feature of the urumi, in exchange for two things that would be absolutely useless for them, indicates to me that you’ve never actually used them at all.
I mean, really? Comparing it to a Petard?
Honestly. Virtual headshaking.
Realistically, I still think the best way is having more healing, so they’ll be topped up when they’re needed. Healing keeps infantry relevant but has little impact in combat.
Edit: yeah, the more I think about it, the obvious choice is to give medical core a healing radius around elephants. That’s synergizes with basically every single one of their options, whether that be supporting archers with elephant archers, supporting elephant archers with infantry, or supporting their unique unit with armored elephants. And at the same time, it doesn’t have any negative impacts on water Maps. I’m thinking something like 1/3 the healing rate on all units within a few tiles of any elephant. Plus, that makes it a far more valid investment in early Castle age, when you might only have one or two elephant units on the field, but you still have a significant body of feudal units remaining, but weakened.