Surely a lasgun on low setting may be used as a writing tool. Hell, the result would be plenty orky as well.
...Do get the barrel OUT of our siege tower before trying that, though.
This exercise
does prove informative to how las weapons work.
Las weapons fire a single burst analogues to a laser bullet, rather than a continued blast like a lance type weapon. This means attempting to write with it ends up like an attempt to write with a stub gun. Someone of skill or dedication could likely pull it off, but it would prove difficult to connect the dots in a meaningful manner.
Las weapons have vertical muzzle climb after firing. Scholars will argue to why, but as a girl from a backwoods feudal world you'll just have to make due without an explanation. Partnered with the first it means that writing is as difficult as with a stub rifle.
Las weapons leave a trail of light that is very visible in the dead of night with your goggles on. Without your goggles on you have a muzzle flash. Not really something you want near an enemy position.
Las weapons make noise. A little whiz at the lowest level, a crack like a grox whip at higher levels. Luckily it is far enough away from a "Daka" that it seams the Orks do not recognize it as the sound of a weapon. Or at least something closely approaching a weapon.
Your lowest setting is apparently "Kill things but don't use too much battery". While this isn't that effective against Orks it does seem to be effective against industrial grade barrels.
In short you shot the barrel, leaving a hole in it and splashing acid on everything nearby. Like if you shot it with a stub-gun. There is the sound of hissing as various nearby vegetation begins to melt down. There are several new holes in the ground from where the acid droplets hit. It is probably going to be hard to move now, at least if you have problems with melting.
It is almost like...whoever designed the lasgun wanted to make it an analogue to a firearm or didn't want such a low tier weapon to have any advantages over higher tier weaponry. How strange.
Well we could tape a grenade to the end and roll it along the train tracks.
I mean, it'd be sacrificing the servitor.. ;-p
But yeah, go with Egan's first if nobody has a better suggestion.
Use Survival to find sap or something to write on the barrel.
You find some perfectly serviceable sap! Sap isn't great at writing either, but it is probably safer to use than knifing the side.
...Too bad the barrel has been shot.