I've been replacing all cast pikes with 0.5mm brass rods so they don't snap off during play, and I find that works great, but what do you do with shorter spears? Do you just take greater care and accept the bendability (breakability) of cast metal? Or do you actually replace those too? If so, do you use different material/technique? I find the shorter lengths don't look as good with brass rods. Thanks in advance for any guidance you can provide.

I've not really experienced too many problems with spears breaking during play. As you've done, my few phalangites have brass rod or piano wire pikes (although in some cases they look more like telegraph poles). The figures I have to be careful with are the Sarmatian and Parthian cavalry. Their lances do bend quite a bit (especially if dropped) but so far I have had only one breakage in use.

I find that a cattle prod is an excellent way of training players  to TOUCH THE BASE NOT THE BLOODY FIGURES !

I find that the problem with breaking off spears and pikes is NOT coming from players touching the minis, rather than from myself wanting to constantly straightening the spears/pike out to look natural, and not like a limp boiled spaghetti. Doing that a few times, the cold hardening of the metal makes the metal brittle and will then ultimately break as a consequence of the metal hardening effect. It only takes a few bends to get to the breaking point.

My solution to this problem is to purchase a dust pan broom with plastic bristles in the desired thickness (takes a little hunting around for the appropriate size), and cut them to length and use them instead of any hard material.

The added bonus for broom bristles is, that they bend when accidentally touched and snap back right into the original straight position without ever breaking off, and even if they ever were to break off, simply replace the broken one for another plastic bristle. This method works particularily well for the ECW pike figures I find.