Yorkaller

Hi, so I'm re-reading Secret History, and there are a few chapters in which Kelsier "takes" objects such as a campfire from the Physical Realm and uses them on the Cognitive Realm. When he does so, he doesn't seem to spend any Investiture of any kind, although in Oathbringer, Shallan has to spend Stormlight in order to make the spheres take a defined form, and also when they want to create ice (I know those two aren't exactly the same thing, but they are kind of similar). So, ¿Why Kelsier doesn't need any kind of Investiture (he mentions that as a cognitive shadow he can't use allomancy) in order to do that, whereas in Roshar they clearly do? My guess is that he is using some of the power he got from Preservation in the Well of Ascension, but I'm not really sure about it, so I wanted to share it with you. (Sorry for my bad writing, I'm not an english native speaker)