To answer this question, grab a jo,boken or tanto and ask a bjj guy to try to take you to the ground and tap you out. First you won't find one who will be willing to even try, second if you do, even if you are awful at weapons the other guy is going to the emergency room, even if he is a Gracie.
Ever notice how in the Gracie propaganda videos and in the UFC the guys adopt a fighting stance and dance around and feint before engaging? This gives you plenty of time to draw a concealed weapon,if the other guy had one he would be trying to kill you with it instead.
As far as bjj guys using eye/groin strikes if you do, anybody who has sparred under those rules enough( never met a bjj or mma guy who has or wanted to, and I asked the crew the current UFC world champion in one weight category trains with) knows that bjj is not designed to deal with that kind of defender.If a bjjj attacker had any ability at using those skills he would use them standing instead of going for the takedown which makes him extremely vulnerable in comparison to doing a double leg takedown on a kickboxer for example.There is a huge difference in these types of standup.Have your sparring partner put on eye protection, a cup and gloves and experience the difference. Claiming that you can use these tactics without ever training them at all or with the same intensity you do your groundwork is the equivalent of a purely stand up guy( Boxer,M.T.,) claiming he can fight on the ground without ever having practiced ground grappling. Spar your stand up this way and the majority of ''fights'' will not end up with both guys rolling around on top of each other, if you are insightful enough you will no longer have any doubts about the effectiveness of aikido for self defense, you might even come to appreciate the practical use of training defenses against wrist grabs
Mike, BJJ is a grappling sports/art. It works best in a given scenario i.e., one-on-one, padded mat, no interference from lava, broken glass etc and no multiple opponents.
Aikido work best when the opponent is so enraged and blind with fury, he lost all rationality that he/she comes charging at you without scant regards to his safety or anyone else. He/She forgot about distancing or balancing.
There, two arts meant for different Combative scenario. Combat is so complex, that is why in any modern army organization, you have the Delta boys, marines, GI etc to serve the different needs.
I see both arts as specialization in their own zone. They both work... in their context.