I would lean towards the fire bola(s) since the thunder bow only has 10_shots unless you know your enemy has specific fire resistance/immunity or an SC where lightning will work.  It gives you the option to switch out one of the two fire bolas for a shield or other 1-hand weapon as well. 
 
I wouldn't add an eye of aiming instead I would provide him a pendant of luck. 
		
	
		
		
		
		
		
		
			
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