a) Mjolnirs have a slight, teensy, tiny, design feature that is of relevance; they're entirely self contained and sitting in open space. As soon as you connect them up to a conductive material, then it changes the thermodynamics. It's pretty obvious, really, that the Mjolnir must have some special feature in order to fit the beam weapon it has, because otherwise you'd be seeing mjolnir-esque beams bolted onto capital ships.
b) There's no evidence that the node exit vector is fixed or predictable. And the default Mjolnir beam is fixed-fire.
c) Shivans haven't needed to send a meson warhead through, yes, but they haven't had to because the GTVA doesn't use tactics vulnerable to such a tactic. They are certainly technically capable of it, which is the whole point.
d) We know there's inter-system communication thanks to the last messages of FS2, amongst others. It'd be trivial to send a scout fighter through; and AFAIK we've never seen the actual start of a Shivan.
e) What seems to be most relevant is...... the Mjolnir was developed as a remote beam cannon. Independent of capships. So what on earth would be the point of taking it and bolting it onto a capship?
Clearly, the relative cost, risk, etc of such a weapon would be considered in creating it - which can only imply it's considered cost effective even given the risk of losing it. If it was going to be prohibitively expensive to lose an RBC, they wouldn't exist.
No army is infinite no weapon is infinite they just look that way till u destroy the last one.
Also i'm pretty sure that these uncharted jump nodes or unstable jumpnodes arent floating aroun everywhere. If they were then the shivans would of bipassed every GTVA atemped blocade and stuff like that. Also the fact that the lucifer used existing jumpnodes other then the one from ross128 means even they are limited in theyr abilaty to travel through subspace. Also thsi is asuming they actualy used a jumnode to get to ross128 and they werent already there in a dormant state sort of like hibernation somewhere on the edge of the sistem.
In FS1, the Shivans were searching for Sol, so couldn't just pick a route but had to attack every system they could. And, yeah, they did circumvent the Antares blockade.
In FS2.... we don't know what they did, or where they were going. The Sathanas did blitz its way through the blockades put against it, though, as did the Iceni....