I just purchased the 'Compendious' Syriac Dictionary (Paine) which is on sale right now. I'm not a syriac expert, but I really, really needed a better lexicon and $20 is just fine. https://www.logos.com/product/27086/a-compendious-syriac-dictionary-founded-upon-the-thesaurus-syriacus-of-r-payne-smith
But while exploring the waters, I ran into the Syriac Heritage volume. Niko's probably already recommended it maybe? Well, I will anyway.
What an amazing volume. When I first saw it, I yawned. Oh, great. Syriac Christianity through the ages. I guess I'm used to 'western' introductions that barely test the waters.
This one's different. Not only does it go into depth on the Christianity part, but the syriac part too. Gorgias has an intro PDF which is quite interesting:
.8524.GEDSH.pdf.
https://www.logos.com/product/42128/gorgias-encyclopedic-dictionary-of-the-syriac-heritage