When trying to review a wood burning tool that is essentially like a pen, I make sure to boil down the method to test a particular tool on 2-3 key parameters since the other things can be subjective.
Fit: If a tool fits well in terms of its ergonomics then it’s a great thing because you don’t want a tool that fits badly since the work requires you to play with fire. Everything from the internal parts like tips should fit properly.
Versatility: There should be enough options when it comes to using the tool with different tips as it increases the use case of what can be done with a single tool and justifies the price.
Durability: Durability is something I always look forward to because it’s directly related to the build quality of a tool. I try to use the tool a little rough to ensure it’s worth recommending.