Thanks for all the great recommendations. I have a KLVUK 15" I love it but it is a bit too short for my dad because it often requires a bit of squatting and bending. if a 18" - 20" were available they would do nicely.
I will check out the Kobra, Chitlangi, Tamrang and the Manakamana in the 20" range.
If you contact Yangdu, make sure you specify the weight range that you would like. There's a lot of variation in weights, even for a specific model and length.
I have a Manakamana Special and an ASTK, and I recall the weights when they've been available. I consider these mid-weight models, not light weight. Of course any particular instance might be lighter than usual, and a bigger, stronger, fitter guy might consider them light weight. Also, the Manakamana Special and Tamangs are few and far between, whereas the Sirupati is one of the more common HI models.
I think your original idea of a Sirupati gives the best length-to-weight option for delimbing trees. The Kobra is more of a fighting blade, and the Chitlangi is essentially a fancier version of a Sirupati, with similar length, weight and blade shape. I happen to have a Kobra that's heftier than most and would do fine at delimbing trees, but it weighs more than most Kobras and is an exception.
For clearing brush a machete should be best. Maybe your Dad's machete isn't a good one, or needs sharpening. Although a Sirupati could clear brush it might be unnecessarily heavy for that purpose. I suppose it also depends on the kind of brush and how much needs to be cleared.
