If there are some rare items in your runescape accounts, do you want them to be tradeable?
No matter your answer is yes or no, you can join Official Rares Discussion Thread to create your topic about rare items in Old School runescape, or you can vote for some topic.
Some untradable rare items are below for your reference.
Jack lantern’s mask
Hats and Scarves from Christmas 2005
For details, you can read