Hm, I was not clear enough but here is the equation:

morale penalty + 1 or 2 ele killed = ele routed

fire arrows= morale penatly
javelins= dead eles

Of course if you dont have one part of the equation you need more from the other. Thus if you dont have javelins you need considerably more fire arrows (and not x-bows!!!), and if you dont have fire arrows you need more javelins.

Fire ballista can work because it has both, it can kill and give them morale penalty at the same time.

Ribault can work if it can kill, I am sure it gives morale penalty.

Musketeers can kill, perhaps combining them with fire arrows would be even more efficient?

ps. giskard, just a non-related question: I see you played Hungary, what was your early strategy? Which province you took first?