I can see two potential improvements that maintain a similar risk.

1. The healing requirement is split, into 50% and 100% thresholds. If you are healed to 100% as it already is, you're fine. If you're healed to 50%, then when it wears off, you get instant Weakness, as if you'd just been raised. <50% and you're dead.

2. If you're not healed to full, then any difference needs to be made up by your MP. If you were healed to 80%, then you lose 20% of your max MP. If you don't have 2000 MP available, you're dead.
This might be my prefered option as you have the possibility of saving yourself by having max MP, or if you've used a TBN and you're ~7000 MP, you may even be able to recover that 30% HP yourself.