Possible Clues:

• Copper - it's invaluable - can be a paralysing poison
• S. Am. arrow poison
• Just see you get it poisonously underdone
• An arrow poison
• See you, that's a most unusual sort of a poison
• Poison remedy around tip of arrow, right?
• Copper encounters unusual poison
• Argon is part of antidote to poison
• Starts to convulse uncontrollably, taking unusual poison
• Antidote contains a resistance for poison