A tacticom, shorthand for tactical computer/communicator, is a portable multipurpose electronic device widely used throughout the Imperium of Sidhae, analogues also existing in it's rival nations.
Tacticoms typically integrate a wide range of functions, but their primary use is that of a computer and communicator, providing the user with tactical data (navigation, combat situation, targeting data, etc.), allowing to exchange that data with other troops and superiors, hack into data terminals and networks, encrypt and decrypt messages, and record video feeds, images and sounds for intel uses. Other functions include the ability to flash-forge various tools and weapons and serve as an ad-hoc power welder.
Tacticoms come in many different models. The newer ones use the "holo" technology, flash-forging their forms and any desired tools or weapons from a swarm of nanites contained in a gauntlet. Older models and those intended for military use are less luminous, using less-obvious hardened touch-screen displays with an optional holographic display function. The user interface is usually haptic. Many different civilian models also exist, the military models generally favouring durability and function over form.
Since tacticoms especially of the all-nanite variety can flash-forge virtually anything within a practical size limit, the user only having to download appropriate apps and blueprints, these machines have become very popular in the civil sphere as well. A weaponized form of this flash-forge feature manifests itself as a glowing holo-blade, a popular self-defense tool among wealthy Sidhae and a favoured and easily-concealed weapon of offense among the Imperium's clandestine operators.
The flash-forge feature essentially entails a cloud of nanites forming hard physical shapes within a self-generated energy field, rather bright luminosity being a partly-unintentional side effect of energizing them, hence the military preference for older touch-screen based models.
The all-nanite or "holo" versions of tacticom are expensive pieces of technology and not widely seen among the general public, most using more traditional and simpler designs.
Abbess Serena Romana and renegade Judicator Alain are both known to be highly-skilled users of dual wrist-mounted holoblades, presumably generated by their sophisticate Judicator-issue tacticoms and their off-hand addons. Other Judicators featured in the Frencoverse only seem to possess one.
Holoblades change colour depending on lethality setting, the non-lethal mode giving them a green rather than yellow-orange glow. It is unknown whether this colour change is due to actual physical changes in the blade material or simply a safety feature. Holoblade matter also seems to be able to conduct electricity, as evidenced by Serena shocking Elena Trotskaya via her holoblades during their first duel in Flight of the Polunochnaya.