Could you help me get the meaning of this sentence? In particular I don't get the meaning of the second part. Context: a swordsman is forced to fight to a common person by his enemies, but he doesn't fight seriously because he doesn't want to harm him. At the end, the enemies kill the common person and make it look like the swordsman did it.

> ここで追いつめられて斬ってしまえる程度なら、いっそ笑って見ていてやれるものを。

My attempt: "If you're going to be cornered here and killed, I'd rather try to laugh" (?)

More context here: https://i.sstatic.net/4ekPn.jpg (I uploaded the page before and the page after too, so the page in question is the second one).
Thanks for your help!