Well, with energy weapons and range, they should be dangerous, but manageable for the most part. Its in numbers or encountering ambush tactics where they are most dangerous to a predator. If they get inside melee range, look out. I really think making acid proof armor a thing hurts the most. I mean even with that armor, there is still a lot of exposed areas, but frankly, your spear should be a 1 or 2 shot weapon, and it better be a lethal strike. That way, the predator essentially has an ammo count for even it's melee weapons. I feel like the xeno being physically stronger should be prominent too. The predator is clearly stronger than a human by a wide margin. The alien should have that advantage over the predator to force it too use skill and tactics and not turn into a pro wrestling match.