"Double Regeneration"
Not "Double Heal"
"Regeneration" is how fast you regain your HitPoints when standing still, fishing, WCing, Cooking, or basically doing anything which you wouldn't normally get hurt from. "Double Regeneration" means you regain HP twice as fast when weilding it.
Regeneration wrote:
Regeneration Re*gen`er*a"tion (-?"sh?n), n. [L. regeneratio:
cf. F. r['e]g['e]neration.]
1. The act of regenerating, or the state of being
regenerated.
"Double Heal" would mean you would get 32 hitpoints off of one Monkfish.
A bracelet of Regeneration would probably save you around 2-3 HP per monkfish depending on what you were fighting.