I'm finding that if I hit a howlitzer with a charge attack on my fireburst brandish and one shot him like a boss, the skull, instead of launching at me, explodes immediately, damaging me before I can even put up my shield. (I usually hold the shield key as I'm releasing the attack so it'll pop up right away) On the other hand if I take him down with a regular sword hit, holding the shield, the skull will bump away and then launch after me.
I'm not sure which is the intended behaviour, though if there's a vote I'll cast mine for the latter.
You can explode Howlitzer heads by hitting them after they break loose. So be careful :P