UNIT - Creature Balance + Visual Changes

Could you please be more specific – which abilities does it conflict with?

And another question: Nargott, what is this setup – I don't quite understand.
==X+
++||+
++||+
++V+
+++A

A - crossbows
X - melee unit (blocker)
+ - cells that can be shot through with armor-piercing attacks
= - cells that cannot be shot through with armor-piercing attacks (safe)
||
V - the blocker's path