MisterRob, true, the Vickie banning the spear would be a good thing for him to refresh his finishers. However, the one caveat is, if you want to be a bit technical, she only said he couldn't use the spear at Royal Rumble or he'd be DQ'ed and lose the belt.
There never was really anything said about using the spear thereafter. If Edge wanted to continue with it, he could. But, given the possible loophole he may find, this would be the perfect way for him to antagonize his enemy. Nothing would please the crowd more than to see him continue taking people out with it. On the upside, you do see him using the downward spiral facebuster which he used to use quite a bit back in the glory days when he was still teaming with Christian, or on the heels of the break up with Christian. I do agree, his spears within the last year or so are not as impactful as they were say, back in 2005. Let's look at the amount of injuries he's battled. He's suffered a torn pectoral, torn achillies heel. Then you add in numerous weapons matches, and age as well. Anyone at his age will tell you they are not as magical in the ring as they were 5-6 years ago. I'm sure even John Cena would say that he is not as light on his feet as he was 5-6 years ago when you add in those same factors.
The finisher is based on gimmick, and ability to sell, and the behaviour behind it. What makes it so impactful is when you see him in the corner with those 'crazy eyes.' I think the lead up to it is what drives it home more than anything. Just like with Randy Orton's punt kick, its all about the theatrics leading up to it. You know he's really not going to kick someone with the same force as a soccer ball. Its about selling the act before/during/after it that sells the impact of it.