I think the important part is the size of the item. There is a table in the Book on page 281. Other than that, if your math is correct, you should be able to put them on. Even multiple effects on one item should be ok, though I would probably hold a player to common sense, since some effects seem too diametrically opposite, that they should not be put on one item. Then again, if you can convince me, that they should, go right ahead.
Warden swords are a bit different, because they are not made by the wizard, but by Lucio, so its math might not be the best thing to base your own items on, since she's probably got some bonuses we don't know about.