Today's strip (http://project-future.xepher.net/harvest.php?strip=08-19)
Don't Demons have the ability to harden their skin? It was kind of thing in Emily (http://project-future.xepher.net/emily.php?strip=01-01) and in the in DMFA. So, unless that sword has some serious magical cutting power it shouldn't be that much of a threat.
Aisha is a professional Demon-hunter, as a Being, with multiple Demon kills under her belt.
I think she's appropriately equipped for her job. xD
My apologies for semi-necroing this, but I only now just noticed this question and wanted to help answer it. ^.^;;
Aisha's sword, Dragonblade, is enchanted to resist magic, so it can cut through spells. From what I've heard speculated, anyway, the skin-hardening is a magic skill, which means it could probably be bypassed by something like that. Being that Aisha's mentor is also a skilled enchanter, she's got some nasty toys stored away. x3
Ah yes, the famous blades of the blacksmith Richard Etcon. :P