How do you keep long thin sword blades from failing on a 1/6 scale print?

Split the sword. I fought the exact same fight on a 1/6 scale piece with a raised blade and lost three prints before I gave in and cut it at the crossguard. What made the seam manageable was not slicing flat through the guard but cutting up into the blade itself a couple millimeters past the guard, then printing a short male peg on the figure's hand end and drilling a matching hole into the blade stub. The joint line ends up sitting along the blade's edge geometry instead of across the flat of the guard, and a little gap-filling putty plus a pass with a sanding sponge makes it vanish under paint. Way easier than hiding a seam on a guard full of detail. For the blade itself once it's seprate, print it steeply angled, like 30 to 40 degrees off the plate, with the edge facing away from the plate side. The layer steps you're seeing come from the near-horizontal orientation, steep gets you thinner effective layers along the edge. Use a tree of fine contact points, small diameter but plenty of them along the lower edge, and accept that the contact zones need a dab of putty. Also slow your lift speed way down for a long thin part like that, the tip flexes during the pull and that's ussually what snaps it mid-print.

On hollowing, I hollow everythign at 1/6 scale, no question. The suction marks around the calf are a ventilation problem more than a hole placement problem. Add a second drain low near the ankle and bump your hole size up, small holes choke on thick-walled areas and the resin pulls against trapped pressure. Thicken the walls a bit around the calves too, thin walls over big flat sections flex and that shows up as those dimples. For cleanup near the guard, skip the sanding sticks and get some abrasive pads or sanding sponges cut into narrow strips. They conform around the detail instead of grinding across it, and a fresh hobby knife tip at low angle does most of the support scar work before any sanding anyway.

One thing that helped me on thin blade parts was letting them cure a bit longer before pulling the supports off. Fully green resin tears out chunks when the contacts pop, but a few extra minutes under UV and the little nubs snap off clean at the surface instead of taking a divot with them. On the peg joint, drill the hole a hair undersized and test fit before glue, because a loose pin in a sword that size will show up as a wobble at the guard every time you look at it. I'd also dry fit the whole arm and sword togather before painting so you know exactly where the seam line lands under the finished pose.

For support scars on visible surfaces like that blade, a fiberglass scratch brush saved me on a wizard figure last year. The staff had fine knuckle detail carved into it and sanding anything just smeared the lines. The brush looks like a mechanical pencil, you push a little fiberglass tip out and it erases the nub right down flush without touching the surrounding detail. Takes a light hand near thin edges though, it will chew into a blade edge fast if you get aggressive with it. I still do the rough removal with cutters first, then a couple passes with the brush and the paint covers the rest. Cheapest fix on my whole bench.

On the blade, what saved me was printing two of them at the same time on the plate. Sounds backwards since thin parts are the problem, but with a spare sitting right next to it I stopped babying the supports and just ran heavier contacts on the spine side where scars don't show. If one tip let go I still had a print, and the good one paid for the resin twice over. For the calf dimples, I started warming my resin in a bowl of tap water before pouring and those suction marks mostly went away. Cold resin is thick resin, it just doesn't flow back fast enough behind the film.

Still learning my way around here so bear with me. I did a 1/12 archer a while back and had a similar headache with the bow arm, except I just made the whole arm a separate part and glued it after painting. Worked okay but the fit was sloppy and I never could get the angle right. When you cut the blade at the guard like that, are you pinning it or is a plain glued joint enough? Also curious if separating the sword changes how you orient the hand, since mine always wanted to droop once it was free of the rest of the model.