Once upon a time, Pillagers had improper arm positioning when wielding weapons other than a crossbow (Example:
MC-139225). Then, they had arms sticking down when wielding something other than a crossbow. In 18w47a, they stick their arms out, regardless of whether or not they are holding a crossbow.
As of 18w47b, they hold their arms in a slightly different position; one folded across the other.
In 18w48a, pillagers holding the improper item have yet another arm position change; this time, one arm sticks all the way through its body and the other sticks out the opposite way it was in 18w47b.