http://www.tip.it/runescape/index.php?rs2monster_id=238

 

I have fought many greater demons, and I have gotten many rune full helms, and not once have I got a rune mace. That drop should be more common since rune full helm is more valuable, the only rune item I got was rune full helm. Let me ask, how do I know for sure the information on that page is correct? I somehow doubt rune mace is dropped by those demons. And I also doubt all the other rune items except for rune full helms.

It's true that rune full helms are more valuable than rune maces, but there is only a very loose correlation between the rarity of an item drop and its value in gp, so you can't expect monster drop tables to always make logical sense. I can tell you from personal experience, however, that I've received every drop listed in the Greater Demon bestiary entry except for the rune spear. If you don't want to take my word for it, you can always check our information against that of other fansites as well.

 

I appreciate your concern, but I am certain that the entry is correct.