The poison damage might need to be upped a bit...
As of about a year ago there was only one properly documented case of a platypus sting. A fisherman found one on a log, thought it was dead or something and picked it up. It twisted in his hand and tagged him with both spurs on opposite sides of the wrist. He was in the hospital for a good long while with a full wrist block (think epidural, but your arm instead of your spine) and was still just shy of insane from the pain.
The venom of the platypus has 2 known active ingredients. The first component causes extreme pain and swelling. The second component is the kicker. It actually increases the nerve pathways ability to perceive pain. This little SOB increases your ability to be hurt at the same time as he hurts you.
And it takes *weeks* to recover the use of an affected limb. The fisherman mentioned above went through extensive physical therapy to recover from the atrophy in the hand he couldn't use until the venom wore off a good deal.
I'm not even sure how to represent such an injury in D&D terms.
Partial paralysis, 3 week duration unless you can make what... a DC 30 Fortitude save to shorten it by half?
The platypus... nature's little demon child. He won't kill you, but you'll wish he did.