I don't know about Halflings, but in my headcannon Thunderstep is trained to hunt gnomes. Stomp the ground to flush them out of their burrows, run them down across open ground...
In the wild elephants tend to freak out when small things move near them - hence their semi-legendary fear of mice - it's not that they're actually afraid of mice, but just any smaller creature, esp. one moving fast, at their feet. That said yeah if you train 'em as animal handling would surely allow, I'm sure they'd be stomping gnomes in no time!
Also yeah Speak with Animals should like, in a training situation, speed up and ease training absolutely massively. It'd be nuts. I'm loving what you did here.
Edit: Show of hands. Who had choice words to say about the Pact of the Blade and the Hexblade in this survey?
I meant to and then forgot
But yeah that is a major issue, Pact of the Blade is a mess w/o Hexblade, not totally unusable, but very close to a trap option, and I've literally seen a player slowly work this out - he was Fiend but went Pact of the Blade, and I didn't want to give unasked-for build-advice, but yeah he eventually realized that actually, the Pact was pretty pointless, he was better off in almost all situations just with good old Agonizing Blast. The DM offered to let him change, but he kept it for the style and because really, Warlock is so well-designed that whilst Chain or Tome would definitely have been more powerful, he was absolutely solid as it was, just gained basically no benefit from his Pact.
I am somewhat worried how WotC plans, if at all, to revise the PHB without somehow invalidating their later splat book options. Like how do you fix the Pact of the Blade without messing up the Hexblade further?
I really think, based on the fact that they're asking about this stuff, we're looking at a highly-compatible 6E or a 5.75E or something, rather than them just "adjusting the PHB" as it were. I mean, they might, but they're asking about like, individual abilities and stuff, and that strikes me as making bigger revisions than anything we wouldn't call an edition change.
It's basically what I've been expecting - most of the changes 5E could do with are player-facing stuff, though I do think monsters could benefit from moving more to abilities and less use of spells, but that's a whole other thread.