for this one, i swapped the head of a Tracker predator for that of a Berserker and gave him a new skin colour. i gave him some extra torso armour & repainted all of the armour in a metallic blue-black and swapped out the hands from another NECA predator so that he could actually grip his spear.
for the weapon, i popped the head off an old broken Alien figure i had lying around and drilled a hole straight through it. i stuck a spare spear thru the hole, sculpted the ragged flesh of the neck around the shaft using green stuff and painted the whole thing up to look nice and bloody :-)