And I have seen, once or twice, my axe strikes showing 'easier strike' while my shield bash et al show 'normal strike'. It doesn't show up often. I'll screenshot it next time.
You're probably referring to the combat opportunities. I know I have never seen a strike at a particular location differ depending on the attack you actually use, unless that attack was a combat opportunity. That said, my skills have never exceeded 11 or 12 (however much I usually dump into it, fighter, and the remainder in dodge/armor/shield use), so maybe it shows up at even higher skill levels.
I tend to agree that weapon skill, and possibly even weapon attributes, should have an effect on what you can expect from a strike. Just because you can hit the target's head with your sword blade, doesn't mean it's necessarily in reach to punch or kick, let alone bite - or that you should be able to shake around a human opponent, as a human, by the upper body after latching on with your upper right tooth!
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Not sure if this is necessarily the place for it, but I had some suggestions about the targeting interface. Chiefly, I'd like to see the opportunity indicator either moved or mirrored to the left side, closer to the keystroke option for selecting that slot. With it on the far side of the window, I find it difficult to see at a glance exactly which component has an open opportunity. I'd also like to see either an indicator when choosing your target that an opportunity is available (simply a ! next to the target in the list will suffice there), or perhaps an announcement that an opportunity is available ("The goblin pikeman stabs you in the left upper leg, but has exposed himself to an opportune strike!"), but those are minor and possibly unnecessary if adventurers are expected to frequently or or always make use of the new targeting system, at least against dangerous targets.
I'd also say that certain combat events should almost guarantee target opportunities, such as when a target falls over (either knocked over, or lost balance due to losing a foot/leg), is stunned, or vomits. However, that's a matter of balance and combat is already pretty easy right now - especially if you have followers who you use as cannon fodder to distract dangerous targets.