Uhm.... weird question. ...

anyway
both are in element body an water elemental would get a slight freeze burn on the upper layer of the water skin but that is just contact damage
The ice user can only fully freeze a water elemental EB when using real force meant to freeze
Th r water user then needs to defrost

and for the weird question
if you losr an arm. Theb you regrow an arm
remember ince you leave the EB you regain the human shape so breaking a arm to grow a leg would not make mich sense on that matter
but also the brain would not know what to do with more legs like that