I know I'm not a Senator, but I think the fact I proposed the bill allows me to briefly chime in here with a correction: this is not taking powers away from the President. Not at all. It just keeps the President from doing whatever the heck he wants with it. Checks and balances shouldn't be confused with eliminating Presidential power.
To reiterate: if this amendment, as I wrote it, passes, the President will still be able to pardon people. It's just that the pardons will be overturned if 3/4ths of all Senators (currently 8/10, to round it up) agree it was a bad decision. That means that 7 Senators can vote against the pardon, and it's not overturned! The President still has the power to pardon whoever he wants (except himself, of course), the only way out of that being if a super-supermajority of all but 2 decide to overturn it!
Hardly stripping the position of all power, as you 3 insinuated, if you ask me.
I get the point, but as someone who was President for two terms, this really is not a necessary reform. If a President's pardon is to be overturned, the only body I would consider appropriate would be the Supreme Court, as it should be based on the law.