I print an extra blank copy of the hero sheet, then use coins to keep track of what abilities I've used. For instance, my main hand has Savagery, and both my head and talisman have Charm. I have this written on my original hero sheet, with the speed/brawn/magic/armor numbers, so I don't have to write anything on my second (blank) sheet. If I use Savagery (a +2 brawn bonus), I put a coin or other marker on my second sheet, showing I've used it up for this combat. If I use Charm (to reroll a die), I have two items with that ability, and I can put a coin on, say, the head item on my second sheet. If I use Charm again, I put a coin on my talisman spot.
Now I get a new weapon on my main hand, which has the Fire Aura ability. I make the change on my original hero sheet, but still don't have to write anything new on my blank sheet. Fire Aura automatically does 1 damage to all opponents, so I just leave a coin on there because I'll be using it all the time, as soon as I can. I use a nickel instead of a penny, because different markers help me remember when abilities are always "on". Now, some opponents are immune to Fire Aura, so I could remove the coin for that combat, knowing it won't do any good.
I also add two boxes, since each different career has two abilities of their own, marking them Career 1 and Career 2. Instead of using a spare hero sheet, I can also just draw boxes on a blank sheet of paper and label them Main Hand, Ring, Chest, etc. You may have to do that for later books, since you get more abilities.