The confused scroll of fire effect (which currently burns your hands and does nothing else) should be upgraded to giving you a cast of burning hands even if you don’t know the spell, while still dealing a bit of fire damage to you since you are confused and did burn your hands.

When you read a scroll of fire inside an engulfing monster, the fire explosion hits it 8 or 9 times instead of just once.

A cursed scroll of fire should create a pool of lava underneath your feet. Possibly only in certain circumstances like with negative Luck.

You can apply a scroll of fire to a greased item to ungrease it. This consumes the scroll.

Reading a blessed scroll of fire allows you to select a spot to center the blast of fire, similar to the selection for a scroll of stinking cloud or the advanced fireball spell. The damage of this scroll is also increased somewhat from what it is now, about four times the current damage, to make it worthwhile to use.