I would suggest a Grohmann No. 1 DH Russell Belt Knife kit ($20-30 on line) and a Finnish made Fiskars retractable blade wood saw (about $10).
The Ghrohmann kits are very easy to make, all you need to do is set the handle scales with the supplied rivets and sand them to match the tang (you can make them water resistant with a bit of mineral oil).
The Grohmann Belt Knife has a full tang so it is sturdy, without being overbuilt so it cuts very well.
The Fiskars saw is fast and efficient…much lighter and safer than an axe too. With the Swisstool that you already have (or just about any SAK with a woodsaw) you should be good to go!
For clearing brush you might want to look into an 18” machete (Ontario D-guard, CS Latin or Tramontina are good ones) for clearing brush (or a 12” version as a large camp knife). The 7/8 lb/14” Fiskars hatchet is a good one if you need a chopper….but I would only suggest a machete or an axe if you have a real need for them, most times a 3 ½ - 5” fixed blade (or a good folder with a strong/reliable lock if you can’t carry a fixed blade) and a SAK with a saw (supplemented with a larger folding saw for heavier work) is all that is needed.
Frank