I never used any fire bombs against that boss, and if memory serves I beat him on my first try. Not having those items regenerate isn't really a bad thing, it just encourages you to level up yourself or your equipment instead of buying healing items. At first I thought that was unfair too, but then a friend showed me that leveling up my mail breaker (short sword) would be more beneficial than trying to rack up enough souls to buy moon grass. I then made more progress in the level. now I shall say this yet again I'll say it again, if you want a game with fast and frantic combat, this isn't your game; but if you want a game with slow-paced, tactical, and thoughtful, combat then Demon's Souls has got you covered. In other words, your preference is not the only one that exists.