I was reminded of the att/str/def ranges and RS gold what supplies/food/armor you should be carrying. He advised me that he should also wear a (rune-full) helmet when facing Elvarg. The person chose to take on Elvarg. I stopped fishing and decided I would go to the fight.
(Aside. Here's how I defeated Elvarg. It's not like I was particularly interested in Runescape, so the Dragon Slayer quest could have been attempted sooner than I did. Attack 41, Strength 55 and OSRS buy gold Defense 45, respectively, pray 43. Two potions of strength (holy symbol), 26 lobsters; rune longsword, full-rune helm, rune body, rune platelegs regular boots; safety gauntlets anti-dragonfire shield.