She sheathed her sword when they arrived, and went to wipe it clean; only to find it spotless.
So there are a couple of possible explanation I can think of for why Hisana's sword doesn't have Kabuto's blood on it.
1) Kabuto is sufficiently capable with Chakra Scalpel that he can parry Hisana's chakra flow with it for a single moment.
2) Kabuto customized his Chakra Scalpel to burn any blood so his opponent has no tangible evidence.
3) That was a Shadow Clone meant to leave nothing behind, and capable of taking serious damage without popping.
4) Kabuto is resilient enough to simply tank a hit without serious damage.
5) The individual in question wasn't Kabuto.
Between the options I find possibilities 1, and 4 unlikely as these wouldn't really fit into the skills needed for a spy, but 3 would be very useful for a spy as it would allow them to gather info with a far lower risk of being caught, and makes it easier to hide their chakra. Furthermore it is something Orochimaru demonstrated in his fight against Team 7 in this quest.
So I'm fairly confident Kabuto was a Shadow Clone, and all trying to kill him alongside Baki would've done is give Kabuto more information on Hisana alongside creating an international incident by killing a Sand Jonin attending as a guest to the Chunin Exam. Although this does raise the issue of why Kabuto used a shadow clone is it because he knows/suspects Hisana has canon knowledge, or simply a habit he established as means of staying alive?
[x] No, you need the surprise!
For the moment I'll vote for this, but there is no guarantee everyone knows, and even if they do they still would lack first hand confirmation.
Although Hisana using her Sharingan to put Temari into a Genjutsu that makes her think Hisana is going for a quick win is probably a good idea just to test the waters on how far the information has spread, and what counters Temari has come up with on short notice.