The only thing that's misleading is probably the name of that ability (Reflective
Shield). It doesn't reflect anything, it only does what the tool tip says, whenever your pet takes dmg (none of that dmg is negated or "reflected"), the attacker takes half of that dmg as well.
It's a bit like the Toxic Skin
ability from Gulp Froglet
. Only instead of 50% of the dmg done it deals 5% of the attackers hp.