just some points about a few weapons. everything is just technical, nothing here is opinion
_In_SanityFlying Guillotine: (in my opinion) the burst damage from use in conjunction with the sandman stun is too high. Stats from use without the sandman seem alright to me (but admittedly I rarely play with or against this weapon when it is used alone)
does 150 damage to anyone "stunned". explosive knockback, natascha slow, and airblast count as being stunned. scouts can toss the cleaver and 1shot a medic who got airblasted or knocked into the air.
_In_SanityBattalion's Backup: Buff feels acceptable, not certain how 'spammable' the buff is in practice though - potentially an area of issue. The increase health coupled with the increased resistances when the buff is used give massive advantages to fights/bombs/1v1s. No obvious downsides beyond the lack of shotgun/gunboats. This weapon feels more balanced that others on this list.
i believe the main issue here is that a soldier who spams can completely negate a kritz uber, since it makes those affected immune to crits. if it's a 5v6 situation, with 6 defending last and the 5 missing their medic, and they've built a Backup with spam damage, if the defending team has a kritz uber, the offensive team can just push in with the backup popped and the uber is negated, and with 30% resistance, they'll probably win the fight anyway unless their DM is shit. if it's a stock uber, the resistance is still really strong and they might win anyway.
_In_SanityDisciplinary Action: Utility, specifically around mid fight timing, forces a team to run it or risk losing mid. Beyond mid fights I don't think it is overpowered, maybe in certain transition situations (or for making other classes more viable in transition). No serious drawbacks compared to stock.
competitive 6s tends to ban any weapons that, when used, force the other team to either run them or be at a disadvantage. this is why the vitasaw is banned.
_In_SanityUllapool Caber: maybe it is because of my time in HL, but this weapon doesn't bother me. Maybe the negatives do not offset the potential to burst in a small AoE. Point blank burst damage might be too high (though you are trading your demo for a low change of killing their medic, provided their medic is paying attention)
the main argument against the caber is that it can be crit boosted
_In_SanityNatascha: I actually don't mind the movement penalty. Value tweaks around this and damage reduction. Current damage reduction is easily negated by coordinated play.
if the duration/intensity falloff was a bit more aggressive, i think this would be okay
_In_SanitySandvich: An additional source of health on demand. Hard counter to any trade/suicide play that only damages the medic. Health can be given to any class, or used to self heal to full health. When used with good positioning or team support the temporary vulnerability is negated
generally banned in 6s because it can heal a med. if you couldn't drop it as often or could only drop it once, or if it didn't heal as much, i think it would be accepted more often