Damn... can't rep any more
- So taking a real close at your gif - I'm gonna go out on a limb and say that this is definitely a deliberate behaviour from the barnacle tip.
Bugged lighting effects are the obvious potential culprit - but I'd expect those to be 'left-overs' from lighting effects that you see as you shoot the barnacle.
Take another look at the gif that @locastan posted: https://gyazo.com/e599e70a866799c68ce86ab32d5c988e
And focus your eyes on the right-hand 'claw'. You can see that it remains 'unlit' for the whole time he's shooting, and then suddenly starts glowing as the rest of the thing does.
That's not a bug imho - that's intentional behaviour.
Yes. Also note the charge animation effect starting to light up from tip outwards. No other rock or surface hit with beams have lighted up like this. I tried...rocks only show a pilot flame at the hit point or do nothing.